OpenFront Nuke Evacuation: Can You Save Troops Before Impact?

Direct answer: move Warships, Trade Ships, Transports, and other movable map units beyond the outer blast radius, because that can prevent their direct deletion. Do not expect an Atom or Hydrogen evacuation attack to shelter its troops: every outgoing attack and Transport cargo pool still takes the proportional casualty calculation. MIRV is different because each pool is checked against a 3% max-Troops floor, but physical blast exposure still destroys the unit.

The decision boundary: evacuate assets, not the ordinary bomb formula

This page solves the few seconds between seeing an inbound nuclear weapon and accepting that the SAM layer may not stop it. The question is not which bomb the attacker should buy, how to place a permanent SAM wall, or how to rebuild after the map has already been cratered. It is narrower: can you save troops or valuable units by moving them, starting attacks, or loading Transports before impact? In v0.34.22, the answer has two layers that the interface makes easy to confuse. The first layer is local deletion. A City, Factory, Port, Missile Silo, SAM Launcher, Train, Trade Ship, Transport Ship, or Warship inside the weapon’s outer radius is deleted when the warhead detonates. A movable unit that gets outside that radius before impact can avoid this local deletion. A structure cannot move, so its only protection is interception, distance, or making the target unattractive before launch. The second layer is troop loss. Once at least one of your owned tiles is among the affected tiles, the game applies a casualty function to your uncommitted troops, to every outgoing attack, and to the cargo of every Transport Ship. Those pools can be far outside the visible circle and still be processed.

That distinction changes the evacuation order. Moving a Warship out of a Hydrogen Bomb’s 100-tile outer radius is valuable because the ship itself survives. Sending 300,000 troops into an attack beyond that circle does not make those troops invisible to an Atom or Hydrogen Bomb. The outgoing attack remains one of your troop pools and receives the same proportional sequence of losses as the pool at home. Loading troops into a Transport does not create an ordinary-bomb shelter either. If the Transport stays inside the outer radius, the local pass deletes it; if it escapes, the hull survives, but its cargo still receives the proportional loss calculation. The right mental model is therefore not “inside troops die, outside troops live.” It is “map objects face a radius check, while troop pools face a player-wide calculation after owned tiles are hit.”

MIRV warheads create an important exception without reversing the model. Their troop formula is calculated separately for each pool and stops producing casualties when that pool is at or below 3% of the player’s maximum Troops. A small detached attack or Transport cargo can therefore receive zero formula casualties from a given MIRV warhead even though a large home pool continues losing troops. That does not make splitting automatically correct. Each detached force has a mission, a route, an opponent, and a recall cost; a later warhead can hit its map unit directly; and stripping the core can let a land attacker win without another missile. The decision is to preserve assets whose movement has a real survival effect, not to click every available action in the hope that location alone defeats a global formula.

Use the real-time nuke defense protocol first while interception is still possible. If the geometry says the warhead will land, use this page for the evacuation decision. After impact, switch to the post-MIRV recovery plan rather than continuing to move pieces according to a pre-impact snapshot. Keeping those jobs separate prevents three common errors: buying a last-second SAM that cannot finish construction, moving ordinary troops as if distance sheltered them from an Atom, and preserving a ship while accidentally abandoning the border that keeps the rest of the country alive.

Two damage systems: affected tiles, troop pools, and the outer circle

Atom and Hydrogen Bombs share the same troop-loss function. For every owned tile of yours selected by the blast, the current value of each troop pool loses 5 * pool / tilesLeft, and the game repeats that step as affected tiles are removed. The home pool, each outgoing attack, and each Transport cargo are calculated independently, but the proportional effect is nearly the same for all of them because the numerator is that pool’s current size. If k of your N pre-strike tiles are affected, the surviving fraction is close to (1 - k / N)^5 for a position that is not down to the last few tiles. That means a strike affecting about 1% of your land removes roughly 4.9% of each ordinary troop pool; 5% removes about 22.6%; 10% removes about 41.0%; 25% removes about 76.3%; and 40% removes about 92.2%. These are bounded examples, not a promise about the visible circle, because only owned tiles actually selected by the blast enter k.

Impact on one player’s pre-strike tiles	Approximate Atom/Hydrogen loss from each troop pool	Does moving the pool outside the circle prevent this?	What distance still saves
1%	4.9%	No	A movable map unit avoids direct deletion if beyond the outer radius
5%	22.6%	No	The hull or ship survives; its troop cargo still takes the pool loss
10%	41.0%	No	Units and structures belonging to any player survive only outside the radius
25%	76.3%	No	Distance protects the object, not the impacted owner’s global pools
40%	92.2%	No	Interception or reducing owned-tile overlap is the reliable prevention

The blast footprint and the unit circle are related but not identical. Atom uses an inner radius of 12 and an outer radius of 30; Hydrogen uses 80 and 100. On normal terrain, inner tiles are selected, while outer-ring territory is selected with a one-in-two random check. Water Nukes use a smoothed irregular boundary between inner and outer radii instead. Troop loss uses the number of your owned tiles that were actually selected. Local unit deletion then checks the full geometric outer radius: ordinary map units inside it are removed even if the outer-ring tile beneath them escaped the territory selection. A Warship at distance 99 from a Hydrogen target is therefore not “half safe” because it sits in the random ring. It is inside the 100-tile unit-deletion circle. A Warship at distance 101 can survive that local pass, although its owner may still lose troops from other pools if the blast selected some of the owner’s land.

MIRV warheads use the same radii concept, with inner 12 and outer 18, but their troop formula is different. Each affected tile removes up to almost 500 troops from a pool according to how far that pool sits above 0.03 * maxTroops. At or below that 3% floor, the formula returns zero. Above it, losses decline as the pool approaches the floor. With a 2,000,000 maximum, the floor is 60,000. Across 250 affected tiles, a 50,000 or 60,000 pool loses zero from the formula, a 100,000 pool loses about 4,618, a 300,000 pool about 25,397, and a 1,000,000 pool about 74,304 under the stated static assumptions. The local outer-radius pass still deletes a unit caught by the warhead. A 50,000-troop Transport outside radius 18 may keep both hull and cargo from that warhead; the same Transport inside radius 18 is deleted. Multiple warheads repeat the decision, so the threshold is a floor per pool, not a shield for a route.

This is why the visible explosion alone cannot answer the evacuation question. You need the bomb type, your owned-tile overlap, your maximum Troops, the size of every detached pool, and the physical location of movable units. The nuke calculator helps compare footprints, while this guide tells you which live actions can change the outcome before impact.

Run RING before impact: recognize, inventory, navigate, guard

Use the RING sequence when the warning appears. Recognize the incoming weapon first. Atom and Hydrogen both use the player-wide proportional formula, so splitting or relocating troop pools does not change their percentage loss. Their difference is footprint: a 30-tile Atom can clip an edge, while a 100-tile Hydrogen can cover a core and many structures. MIRV means repeated radius-18 warheads and a per-pool 3% max-Troops floor. Do not use the MIRV floor while the incoming object is a Hydrogen Bomb, and do not use the Hydrogen percentage table as if one MIRV warhead erased the same share. If the interface only shows the warning and trajectory, identify the weapon from that warning before issuing an evacuation attack.

Inventory what can actually be saved. Put movable map units in one list: Warships, Trade Ships, Transport Ships, and any other unit with time and a legal route to leave the outer radius. Put fixed structures in another: Cities, Ports, Factories, Silos, SAM Launchers, Defense Posts, and rail infrastructure. Fixed structures cannot be evacuated. Then list troop pools: home Troops, each outgoing attack, and each Transport cargo. Against Atom or Hydrogen, location cannot remove those pools from the casualty calculation if your land is affected. Against MIRV, compare each pool to 3% * maxTroops; do not compare to current Troops or to the Transport’s capacity. This inventory stops you from spending the whole warning window moving the wrong resource.

Navigate only when the move crosses a meaningful boundary. For a Hydrogen target, a movable unit must get beyond 100 tiles from the destination; for an Atom, beyond 30; for a MIRV warhead, beyond 18. Add a margin because the unit must be outside when detonation resolves, not merely pointed outward. A Trade Ship already 95 tiles from a Hydrogen target with a clear route is a better evacuation candidate than a Warship 20 tiles away whose path crosses the target. Do not recall an outgoing land attack merely to bring its troops “home” against an ordinary bomb: both pools receive the formula, and recall itself can burn 25% of the returning attack. Change an attack only if its military objective has become invalid, not because the home tile looks safer.

Guard the position that must still exist after impact. Keep enough reserve to stop the land follow-up, preserve a connected City or income node outside the target zone, and note the attacker’s other loaded Silo tubes. Saving two Warships is not a win if the evacuation empties the border and the attacker walks into every surviving City. Conversely, sacrificing a low-value Trade Ship may be correct if moving it would cancel a route, consume attention, or pull an escort away from the only surviving Port. Guard also means switching plans at detonation: recount tiles, Troops, City levels, and ready SAM slots. The pre-impact RING snapshot expires the moment the blast changes the map.

RING produces a short action list rather than a panic burst. A typical result is: keep the SAM decision automatic, move one high-value Warship beyond radius, leave the land attack running because ordinary-bomb distance does not shelter it, protect the second City, and hold a border reserve for the follow-up. On a MIRV warning it may instead be: spread movable ships away from visible target clusters, keep two already-small attacks below the 3% pool floor if they have valid objectives, avoid launching a meaningless third attack, and prepare to repeat the check for the next warhead. The framework works because each verb corresponds to a separate implemented test: weapon type, object list, geometry, and post-impact position.

Scenario one: an Atom clips a broad frontier while an attack is active

Assume a public FFA at v0.34.22. You own 10,000 tiles, have 1,000,000 uncommitted Troops, and are running one 300,000-troop attack on a neighbor. A levelled Warship and a 40,000-troop Transport sit near the contested coast. An Atom is inbound toward a frontier City. For this scenario, assume the selected blast tiles include 500 of your owned tiles, exactly 5% of your pre-strike territory. Also assume the Warship begins 25 tiles from the target, the Transport begins 34 tiles away, and both have legal routes that do not cross the target. The outer Atom radius is 30.

The proportional calculation leaves about 77.4% of every ordinary troop pool. Your home pool falls from 1,000,000 to roughly 773,740. The outgoing attack falls from 300,000 to roughly 232,122 even though it is fighting beyond the visible blast. The Transport cargo falls from 40,000 to roughly 30,950 because its location does not exempt it. Starting a second attack with half the home army just before impact would create another pool, but both new pools would lose about the same percentage; it would not preserve the combined total. Recalling the existing attack would be worse if the normal 25% recall loss applies, because you would pay that loss and still expose the returned pool to the Atom formula.

The local-unit decision is different. The Warship at distance 25 is inside radius 30 and will be deleted if it stays. Moving it beyond 30 before detonation can save the entire ship. The Transport at 34 is already outside the local deletion circle, so moving it farther does not reduce the proportional cargo loss; it only changes route safety. If the City, Port, or SAM at the target remains inside radius 30, it cannot be evacuated and will be deleted. The useful actions are therefore to move the Warship across the outer-radius boundary, keep the Transport on a route that remains valid after the coastline changes, leave the outgoing attack alone unless its objective fails, and hold enough remaining home Troops to defend the newly shortened border.

The attacker’s counterplay explains why this is not a free rescue. They can aim the Atom so its 30-tile circle catches both the City and the Warship’s likely retreat lane, launch a land attack to pin the Warship’s supporting coast, or follow the Atom with a conventional push while your home pool is about 22.6% smaller. They can also target a compact core where 500 selected tiles are a larger share of your country, increasing the percentage loss. Your answer is not to promise the 22.6% figure before you know k. Estimate how much of your own territory sits in the footprint, prioritize units that can actually cross radius 30, and treat every percentage as a planning scenario rather than a UI forecast.

This scenario shows the evacuation rule in its cleanest form. Geography can save the Warship because the Warship faces a local radius check. Geography cannot save the outgoing attack from the Atom’s troop calculation because that attack belongs to the impacted player. The right move preserves the expensive object and avoids adding a pointless recall loss. If you instead need to decide whether the attacker should have bought the Atom at all, that is the separate Atom versus Hydrogen versus MIRV decision; here the purchase is already flying, and only your response remains.

Scenario two: a Hydrogen Bomb covers forty percent of a compact core

Assume a compact late-game country still owns 10,000 tiles and has 1,000,000 home Troops, two outgoing attacks of 250,000 each, one 120,000-troop Transport, two Warships, three Cities, a Port, a Factory, and one rear Missile Silo. A Hydrogen Bomb is aimed at the central City cluster. For this bounded scenario, 4,000 of the player’s owned tiles are selected, or 40% of the pre-strike total. One Warship and the Transport are 70 tiles from the target, the second Warship is 108 tiles away, and the rear Silo is 115 tiles away. The weapon’s inner radius is 80 and its outer radius is 100.

The ordinary-bomb formula is devastating because the tile share is large. Each troop pool keeps about 7.8% and loses about 92.2%. The home pool falls from 1,000,000 to roughly 77,700. Each 250,000 attack falls to roughly 19,400. The 120,000 Transport cargo falls to roughly 9,300. Splitting the home pool into more attacks before impact does not change the combined percentage in a useful way: each pool receives the same proportional sequence. Loading more troops into the nearby Transport does not help; its cargo receives the formula and the hull is inside radius 100, so the local deletion pass removes the unit anyway. Against this Hydrogen target, “evacuate the army” is mathematically the wrong instruction.

Asset evacuation still matters. The Warship and Transport at distance 70 cannot merely start moving; they must cross outside 100 before detonation. If one can make that distance and the other cannot, save the Warship if its route and future naval task have more value than the Transport’s already-doomed cargo. The Warship at 108 is beyond the local circle and should not be pulled back through it. The Silo at 115 survives the direct deletion pass, giving the defender a real counter-threat after impact. The Cities, Port, Factory, SAMs, and other fixed units inside radius 100 cannot be moved. Their only last-second protection is an automatic intercept that actually has geometry and a loaded slot. If that check has already failed, attention belongs on surviving assets and the post-strike border.

The strategic objective is not to save a percentage point; it is to retain a playable state. Keep the rear Silo connected, preserve the outside Warship, and identify which land corridor remains after 4,000 tiles are relinquished. Do not issue an ambitious counterattack from the 77,700 survivors before checking whether another enemy Silo tube is loaded. If a City beyond the target adds enough max Troops to make recovery viable, protect that City rather than escorting a low-value ship. If the blast severs the Transport route, the hull could survive outside radius but still become irrelevant. A surviving object without a route or job is not automatically a successful evacuation.

The attacker can make the dilemma harder by centering the Hydrogen on the evacuation exit rather than on the most valuable single building, or by timing a land push so the surviving corridor is already under pressure. The defender counters before launch by spreading irreplaceable fixed structures farther than one Hydrogen diameter where the map allows, layering SAM coverage, and avoiding a single compact cluster that puts 40% of all owned tiles under one target. Once the warning appears, those design choices are already fixed. RING therefore produces a severe but clear list: cross the 100-tile line with units that can make it, do not split troops for false shelter, preserve the rear core, and prepare the recovery playbook from the actual survivors.

Scenario three: MIRV pools, the three-percent floor, and repeated warheads

Assume the same player has a maximum of 2,000,000 Troops when a MIRV spreads across the map. At the moment one warhead detonates, the player has 1,000,000 home Troops, a 300,000-troop land attack, a 100,000-troop second attack, and a Transport carrying 50,000. The per-pool floor is 3% of maximum, or 60,000. For this scenario, that warhead selects 250 owned tiles. All four troop pools belong to a player whose land is affected, but each pool enters the MIRV formula with its own current size.

After 250 affected tiles, the home pool falls by about 74,300 to roughly 925,700. The 300,000 attack falls by about 25,400 to roughly 274,600. The 100,000 attack falls by about 4,600 to roughly 95,400. The 50,000 Transport cargo is already below the 60,000 floor, so the troop formula removes zero from that cargo. These numbers are outputs of the stated static example, not a general per-warhead promise: change maximum Troops, selected tiles, starting pool size, or prior warheads and the result changes. The structural conclusion is stable, however. MIRV evaluates each pool separately and tapers its losses toward 0.03 * maxTroops; Atom and Hydrogen do not use that floor.

Physical position still decides whether the Transport exists. A MIRV warhead has outer radius 18. If the 50,000-troop Transport is 12 tiles from this warhead’s destination, the local pass deletes the whole unit even though its troop pool would receive zero formula casualties. If it is 25 tiles away, it can survive both checks for this warhead: outside the local radius and below the formula floor. The next warhead may have a different destination, so the safe action is to navigate away from target clusters, not to assume one distance protects the ship from the entire carrier. A Warship or Trade Ship faces the same local radius-18 deletion but does not have a troop cargo pool; moving it between gaps in the spread can preserve the object.

Could you split the 300,000 attack into several sub-60,000 attacks? The formula implies that a pool at or below 60,000 receives zero MIRV troop casualties, but the match decision has other costs. Each attack needs a legal enemy and useful objective. Detached forces can be defeated by defenders, cannot protect the home border while committed, and may pay the 25% land-recall penalty if recalled. The opponent can launch conventional attacks while your home pool is fragmented, and repeated warheads can destroy the terrain or map units supporting those forces. Treat the floor as a reason not to recall an already-useful small attack into a large exposed home pool, not as an instruction to spray meaningless attacks across the map.

Repeated warheads also move pools toward the floor rather than guaranteeing elimination. In the same 2,000,000-max example, 700 affected tiles take the 100,000 pool to roughly 88,400, the 300,000 pool to about 234,900, and the 1,000,000 pool to about 801,600, while the 50,000 pool still sits at 50,000 if no local unit deletion or combat changes it. Other warheads, land battles, growth ticks, and changing territory can alter maximum Troops between impacts. Re-run RING instead of freezing the first calculation. Preserve valid small missions, move exposed units outside each radius-18 target, and keep enough home force to survive the attacker’s non-nuclear follow-up.

Failure modes and opponent counterplay

The first failure is treating the visible circle as the casualty boundary. That saves a hull and then surprises the player when its cargo or a distant land attack loses troops. Counter it by writing two separate lines: “objects inside outer radius” and “pools owned by the impacted player.” Move objects across the first boundary; calculate pools under the second. The second failure is treating all three weapon types as one formula. The Atom and Hydrogen proportional model can erase a large share of every pool when a large share of territory is selected. The MIRV model instead has a 3% max-Troops floor per pool. Counter this by recognizing the weapon before moving anything. A correct action for a small MIRV pool can be useless against Hydrogen.

The third failure is using recall as evacuation. A land recall normally discards 25% of the returning force. Against Atom or Hydrogen, the returned troops still belong to the impacted player and remain in a processed pool. You can therefore pay a recall loss without reducing nuclear losses. Recall only when the attack itself became strategically wrong: its route will be severed, its target no longer matters, or the surviving border needs the remaining 75% more than the attack needs the full force. For the detailed decision, use the recall-or-finish guide. The fourth failure is moving a unit to the edge rather than beyond it. The local deletion check uses the outer radius; a Hydrogen unit at distance 99 is inside, an Atom unit at 29 is inside, and a MIRV unit at 17 is inside. Give the route margin for movement resolution and do not count a planned path as completed movement.

The fifth failure is splitting every force to exploit the MIRV floor. The opponent’s counter is conventional pressure. A home pool stripped into many small attacks may take less formula loss per pool, yet lose the capital to a land push, leave Defense Posts unsupported, or require expensive recalls. The formula protects no objective by itself. Only detach a pool that already has a bounded mission, a viable route, and a stop condition. The sixth failure is saving mobile units while losing the economy that gives them purpose. A Warship without a reachable Port cannot use active repair; a Trade Ship without a route produces nothing; a Transport without a safe shore is stranded. Rank evacuations by post-impact job, not by purchase price alone.

The attacker has matching counterplay. They can aim between structures so the outer radius catches likely ship exits, choose Hydrogen when the compact tile share makes the proportional loss decisive, or use MIRV spread to force many radius-18 decisions that overload attention. They can start land attacks before impact so the defender cannot empty the core safely, and they can hold a second Silo tube for the route that survived the first blast. A defender answers earlier than the warning by separating fixed assets, keeping two independent corridors, and placing automatic SAM coverage over the structures that cannot move. During the warning, the defender answers with a short action queue rather than a complete redesign.

The final failure is using calculated examples as a combat forecast. The interface does not show k, the exact number of owned tiles the random outer ring will select. Water Nukes change boundary generation. Multiple players can own tiles in the same footprint, and each gets a separate affected-tile count. Territory can change between launch and detonation. Use 5%, 10%, or 40% as scenario inputs that reveal sensitivity, then read the actual post-impact result before counterattacking. The numbers make decisions clearer; they do not make the random boundary or the live board deterministic.

Mode, map, and team adjustments plus the final checklist

Map shape changes which half of evacuation is valuable. On a small or compact map, a 100-tile Hydrogen circle covers a larger share of both the board and a player’s territory, so the proportional loss can dominate and there may be no legal path for a ship to cross outside the radius in time. Prioritize interception, a separated rear core, and a surviving land corridor. On a large continental map, ships and Transports may have room to leave the local circle, but a dense central country can still place a large tile share under one Hydrogen target. On archipelagos, moving a Transport beyond the radius can preserve the hull while the blast destroys its destination shore. Check the route after the coastline changes before counting that unit as usable.

Water Nukes alter terrain and use a smoothed irregular boundary for selected tiles. The inner and outer radii still define the zone, while the exact affected-tile count depends on the generated boundary and impassable terrain. Local units inside the outer radius remain exposed to deletion. A retreat across water can save a Warship geometrically, yet the new water can disconnect Ports, Cities, rails, and land counterattack routes. In Water Nukes mode, add one RING question: what route exists after the land becomes water? The Water Nukes guide covers the terrain and routing consequences; this page continues to own the troop-pool and movable-asset decision.

Team games separate ownership. The troop formula is applied to a player whose owned tiles were selected, not automatically to every teammate. A teammate’s Warship inside the outer radius can still be deleted by the local pass, even when that teammate owns no affected land and therefore does not enter the casualty loop for that warhead. This makes ownership and formation important. Do not park allied fleets over one teammate’s likely Hydrogen target, and do not assume the absence of team-wide troop loss protects allied units physically inside the circle. Coordinate exits so two players do not choose the same narrow lane, and leave at least one teammate with a connected reserve able to cover the damaged player’s border.

FFA adds a third-party problem. A technically perfect evacuation can expose the surviving units to a different neighbor, and a detached attack can hand territory to the player who did not spend the nuke. Evaluate destination safety, not just distance from the target. No Alliances removes one diplomatic complication but not the formulas. Overtime or Doomsday can make land share more important than preserving a ship; if moving the fleet lets the enemy cross the current victory line, hold the line even at the object’s cost. Infinite Troops or host modifiers can change the practical value of the troop calculation, so read the lobby settings before relying on a standard scenario.

The final checklist is short. Identify Atom, Hydrogen, or MIRV. Estimate how much of your land the footprint can select. Mark every movable unit inside outer radius 30, 100, or 18. Separate those objects from home, attack, and Transport troop pools. Against Atom or Hydrogen, do not split or relocate pools for imaginary immunity. Against MIRV, compute 3% of maximum Troops and preserve already-useful small pools without weakening the core for no reason. Move only units that can cross the boundary and retain a post-impact job. Keep a land reserve, a connected City or income node, and awareness of additional Silo tubes. At detonation, discard the old estimate and recount.

These rules apply at the formal OpenFront v0.34.22 Release. The tagged nuclear execution defines affected tiles, troop pools, Transport handling, and local unit deletion; the tagged configuration defines radii and both casualty functions. The v0.34.22 patch itself changes billing, private-lobby control, Firefox Android startup, and loading presentation, not these nuclear rules. That version boundary matters: if a later Release changes either formula or the local radius pass, recalculate the scenarios before keeping the same evacuation order.