OpenFront SAM Targeting Priority: Which Incoming Nuke Your SAM Actually Intercepts

Direct answer: your SAM shoots the highest score, and score is type plus landing distance

When two enemy nukes are in the air at the same time and your SAM has one shot left in its cooldown, the instinctive move is to assume the SAM will save your most valuable target, and the correct correction is that the SAM has no idea what is valuable to you. It has no value table, no “protect the hydrogen” rule, and no awareness of your gold, your tiles, or what a warhead on your crown costs you. It runs one arithmetic comparison for every targetable nuke in the air and fires at the one with the highest number. In the v0.34.24 source that number is a three-part sum: a fixed type bonus of 70,001 that only hydrogen bombs carry, a distance bonus of 200,000 minus 1,000 for every tile of Manhattan distance between the SAM and the nuke’s predicted landing tile, capped at zero, and an urgency bonus of 10,000 minus 100 per tick remaining before impact, which is small enough that it only separates two targets that are otherwise nearly tied. The distance term is measured to the landing point, not to the nuke’s current position in flight, which is the single most-misread line in the whole mechanic. The practical upshot is that a hydrogen bomb is worth exactly 70,001 points of priority over an atom bomb, and 70,001 points of distance bonus is exactly 70 tiles of landing distance, so a hydrogen whose warhead is predicted to land 71 or more Manhattan tiles further from your SAM than a rival atom bomb loses the engagement to that atom bomb. Your SAM’s one shot per 90-tick cooldown goes to the near atom, the hydrogen lands unintercepted, and the hydrogen’s 5,000,000 cost never mattered to the SAM at all. Everything on this page is the arithmetic of that race, the two scenarios where you will meet it, and the placement and timing moves that change who wins it before the first missile is even launched. The table below is the whole mechanic compressed to one screen; if you only remember one number, make it the 70-tile column.

The score formula: type, distance, urgency

The targeting system in v0.34.24 scores every candidate nuke with one formula and picks the maximum. The formula is score = typeBonus + distanceBonus + urgencyBonus, and each term is worth breaking apart because each one has a different behavior at the edge of its range. The type bonus is a flat 70,001 for a hydrogen bomb and exactly zero for everything else: atom bombs and MIRV warheads both carry no type bonus, so in the SAM’s eyes a MIRV warhead is an atom bomb and the most expensive thing in the game (a MIRV at 25,000,000 plus 15,000,000 per additional launch) is indistinguishable from the 750,000 atom. The distance bonus is max(0, 200,000 - 1,000 x d), where d is the Manhattan distance from your SAM’s tile to the nuke’s predicted landing tile. Manhattan distance means horizontal plus vertical tiles, no diagonals, so a landing point 50 tiles east and 30 tiles north of your SAM is 80 tiles away and costs 80,000 in distance bonus. The bonus decays linearly at 1,000 points per tile and floors at zero, which means past 200 tiles of landing distance the distance term contributes nothing at all and the target is being scored on type and urgency alone. The urgency bonus is max(0, 10,000 - 100 x t) where t is the tick count before the nuke impacts; a nuke with 40 ticks to impact earns 6,000, one with 90 ticks earns 1,000, and one with 100 or more ticks earns nothing. Because the urgency bonus spans at most 10,000 points while the hydrogen type bonus is 70,001, urgency can never by itself flip a hydrogen-vs-atom decision that is more than about 10 ticks apart in timing; it is a tiebreaker for same-type targets, not a priority override. The candidate pool is the enemy atom bombs, hydrogen bombs, and MIRV warheads within the detection range, which is 600 tiles (four times the maximum SAM range of 150), filtered to the ones the SAM can actually reach for an interception within its firing range before impact. So the SAM is not “looking at everything on the map”; it is looking at every enemy nuke whose landing point is inside a 600-tile window and whose interception point is inside its current firing range, and it is ranking that window with the three-term score. Three edges of this window are worth naming because each one is a place a defense quietly dies. The first is the floor at zero: a landing point more than 200 Manhattan tiles from your SAM scores its distance bonus as exactly nothing, so two far landings compete on type and urgency alone and the hydrogen almost always wins that far contest, which is why a SAM placed very far from your own core is a SAM that will always shoot the big distant nuke and almost never the cheap one aimed at you. The second is the detection gate: a nuke whose landing is outside 600 tiles is invisible to this SAM’s score and gets no shot at all, which is why a single SAM cannot be your whole defense on a wide map and why the extra launcher on the far side of your territory is the one that exists to score the landings the center launcher cannot even see. The third is the firing-range gate, covered in the placement section, which is the third place a perfectly-scored target still gets through because the SAM is not allowed to reach the interception point.

The 70-tile buffer: when a near atom beats a far hydrogen

The number that turns this formula into a decision is 70 tiles. A hydrogen bomb’s only priority edge over an atom bomb is its 70,001 type bonus, and because the distance bonus erodes at exactly 1,000 points per tile of landing distance, that edge is exactly 70 tiles of latitude: a hydrogen predicted to land 70 Manhattan tiles further from your SAM than a competing atom bomb is scored at a tie, and one predicted to land 71 tiles further is scored lower, so the SAM fires at the atom. Work the concrete arithmetic. Put a level-3 SAM at the origin. An atom bomb is inbound on a landing tile 30 tiles away, giving it a distance bonus of 170,000 and a type bonus of 0, so its score is 170,000 before urgency. A hydrogen bomb is inbound on a landing tile 100 tiles away, giving it a distance bonus of 100,000 plus the 70,001 type bonus, for a score of 170,001 before urgency. The hydrogen wins by 1 point of type bonus. Now move the hydrogen’s landing to 110 tiles away: its distance bonus drops to 90,000, its total is 160,001, and the atom at 170,000 wins the engagement by roughly 10,000 points. Both nukes are still inside the 600-tile detection window and both are reachable, so the SAM is genuinely choosing between them, and it is choosing the atom. This is why the community’s “the SAM will always save the big one” intuition is wrong in the endgame: a player who launches a hydrogen deep into your territory while sending a cheap atom at your center has not sent a distraction, they have sent the target the SAM will actually shoot, because the atom’s landing point is closer to your SAM than the hydrogen’s landing point minus 70. The flip side is just as useful. If you are defending and you cannot stop a two-nuke launch, you can try to make your own hydrogen’s landing point the closer one relative to where your SAMs sit, because the hydrogen you want intercepted is the one whose landing tile is the closer one on the Manhattan grid. The 70-tile buffer is the whole rule: measure both landing points, subtract 70 from the hydrogen’s distance, and the side with the smaller adjusted distance is the SAM’s first shot. One more way to think about it that makes the buffer concrete in the middle of a game: the buffer is not a circle you can see on the map, it is a line you draw from your SAM to the hydrogen’s landing point, and anything the enemy wants protected has to land on the hydrogen side of that line or the hydrogen is the shot that gets spent. When the enemy sends a hydrogen at your crown and you can see it coming, the line is the crown landing minus 70 tiles back along the approach axis, and every atom they launch that lands closer to your SAM than that line is a decoy that will win the engagement for itself and leave your crown exposed, which is exactly the trap the next two scenarios walk through and out of.

The cooldown cap: one shot per 90 ticks, and what that means for a wave

The second constraint on your defense is not which nuke the SAM shoots; it is how many it can shoot. Every SAM launcher has a 90-tick cooldown between interceptions, and a missile in flight from a normal silo range takes on the order of 60 to 100 ticks to travel, depending on the range the launch is made at. That combination is the ceiling on everything you can defend with a single SAM: it can spend at most one shot while a given wave is in the air, and a wave is only “in the air” for the flight window of the missiles it contains. A single atom on a short range is one shot and one SAM can handle it. A hydrogen plus a near atom is two targets and one shot, and the score formula decides which one dies, which is the race in the previous section. A MIRV is the case that breaks the whole picture, because a MIRV detonates into multiple warheads and the targeting system treats every MIRV warhead as a separate targetable nuke, each with its own landing point, its own distance bonus, and its own claim on your SAM’s cooldown. A MIRV spread across five landing points is five separate candidates in the score pool, and your single SAM can intercept at most one of them per 90 ticks, so a five-warhead MIRV against a one-SAM defense is four guaranteed landings no matter how the scoring works. This is why the community’s “hydro plus atom combo pierces a big SAM stack” observation is really about cooldown arithmetic and not about target selection: the combo does not confuse the SAM, it just has more warheads than shots. The planning number to keep is therefore the ratio of enemy warheads per wave to your SAMs per 90-tick window. If the enemy can launch 4 warheads in a wave and you field 4 SAMs across the front, each SAM gets at most one shot in the window and the defense holds only if every shot lands on the warhead whose landing is the one you can least afford; if the enemy fields 8 warheads, no amount of SAM placement rescues a 4-shot defense, and the correct move stops being “aim better” and becomes “make the launch more expensive” or “force the wave into a range you do not defend.” The reason this ratio is the number to keep, rather than the targeting priority, is that in a MIRV wave the targeting priority is almost a non-issue: the SAM will shoot whatever scores highest, and in a wave where every warhead is an unboosted atom-score target, the highest score is just the closest landing, so the SAM does the one sensible thing and then runs out of shots, which means the defense question collapses entirely into “how many warheads per wave can my SAM count cover,” and that is a count question, not an aim question.

Scenario 1: hydrogen deep, atom close — the SAM picks the atom

Run the scenario with exact numbers, because the version where this is a vibe is the version you lose. You sit a level-3 SAM launcher at the center of your core, range now around 142 (150 minus 480 divided by 8). Your enemy launches a hydrogen bomb at your crown, which lies 100 Manhattan tiles from your SAM’s tile, and on the same tick launches a 750,000 atom at your secondary factory, 25 Manhattan tiles from the SAM. The hydrogen’s score: distance bonus 100,000 plus type bonus 70,001, roughly 170,001 before the small urgency term. The atom’s score: distance bonus 175,000, so roughly 175,000 before urgency. The atom’s landing point is 75 tiles closer than the hydrogen’s, which is more than the 70-tile buffer, so the SAM fires at the atom. Your factory keeps standing behind its blast and the hydrogen reaches your crown with no interceptor in the air. The move that fixes this is a placement move, not an upgrade move: a second SAM positioned 70 tiles toward the crown, so the crown landing is now inside a short distance bonus for that SAM and the hydrogen’s adjusted distance is smaller than the atom’s from either SAM’s position, flips the engagement to the hydrogen without spending a single upgrade point. The second move is a timing move: if you can detect the launch, the hydrogen’s landing is the one you want your best SAM to own, so shift your intercept budget toward the crown before the atom’s closer landing expires its urgency. The third move, when you cannot win either race, is the value move: accept the hydrogen on the crown only if the crown’s blast cost is smaller than the cost of the SAMs and tiles you would spend to cover a 100-tile radius with a second launcher, which in most endgame positions it is not, so you should not accept it. The failure mode to recognize on your screen is the one where the SAM visibly tracks a small incoming missile while the large one keeps climbing: that is not a bug, that is the distance bonus doing exactly what the formula says, and the correction is the second SAM toward the crown, not more gold into the one you already have. If you have already spent the gold on the first SAM and the enemy launch is in the air, the only remaining lever is the timing of your other structures, because you cannot re-score a missile that is already climbing, but you can still decide which tiles are worth saving by the blast by pulling your most valuable buildables out of the crown’s blast radius before impact, which is the same instinct that drives the nuke flight trajectory read, except applied to your own placement instead of to the enemy’s arc.

Scenario 2: a MIRV wave against a four-SAM front — cooldown math decides

The endgame version of the problem is a MIRV, and it is worth running because it is the case where the targeting priority question disappears and the cooldown question takes over. Your enemy has launched a MIRV, 25,000,000 for the first and 40,000,000 for the second launch in the same game, and the warheads spread across five landing points: two on your crown, one on your missile silo line, one on your core, one on your trade port. You field four SAM launchers across the front, two at level 3 near the crown and two at level 2 flanking. The targeting system now sees five separate nuke units, not one, because MIRV warheads enter the candidate pool as individual targets with zero type bonus, so every one of them is scored like an atom bomb. The two crown warheads score highest because their landing points are closest to your two level-3 crown SAMs, and each of those SAMs has one shot in the 90-tick window. Best case: both crown SAMs intercept the two crown warheads, your crown holds, and the silo, core, and port warheads land on three separate tiles with nothing to intercept them. That is a defended crown and three landings you have to live with, and the correct reading of that outcome is that your four-SAM front was built for a two-warhead wave, not a five-warhead one. The move that changes the arithmetic is not adding a fifth SAM; it is moving the two flanking SAMs to landings two and three, because a SAM whose landing bonus on a warhead is negative in the score race is a SAM that will shoot nothing useful and might as well be covering the next most expensive tile. The deeper move is the economic one: a second MIRV launch costs the enemy 40,000,000 and your whole front costs you far less than that, so the winning endgame posture is usually the one that makes the enemy’s second MIRV unaffordable, which is exactly the posture your MIRV price ladder walks through, and the posture that makes any MIRV you do send land on the tiles you can afford to lose, which is the landing-point planning in the MIRV guide. The move to avoid is the one that feels right in the moment and is wrong in the math: adding a fifth SAM on the assumption that more shots automatically mean more landings prevented, when the fifth SAM placed on the wrong axis will score the same closest warhead as the fourth and intercept the same target, so the fifth SAM only helps if it sits close enough to a warhead the other four are too far from to score, which is why the fix is repositioning the two flanking SAMs to landings two and three and not buying a sixth launcher on the far side of the map where it will time out before it ever scores a useful target.

Placement and range: where the SAM sits is a score input

The most common mistake this page exists to kill is treating SAM placement as a coverage problem, “where does this circle reach,” when it is actually a scoring problem, “which landing point does this SAM give the best score to.” A SAM two tiles away from a landing point is worth 2,000 points of distance bonus more than a SAM two tiles away in the other direction, and because the hydrogen’s type bonus is exactly 70,001, a SAM whose position puts the crown landing 70 or more Manhattan tiles further from it than the rival atom’s landing has already lost the priority race before either missile is fired. The concrete rule is to place each SAM so that the landing points you can least afford are the shortest Manhattan distances from it, and to place the second SAM of any pair on the axis between the two most expensive landing points, not outside them, because outside placement helps the farther landing and hurts the nearer one, which is backwards. Range matters in the same score, not just the score: the firing range is 150 minus 480 over level plus 5, which is 70 tiles at level 1, about 96 at level 2, about 120 at level 3, about 134 at level 4, and approaching 150 at high levels, and the SAM will not even compute an interception for a nuke whose interception point is outside that range, so a level-1 SAM placed 70 tiles from your crown cannot intercept a crown landing at all and its targeting priority is irrelevant to you. That is why the level-2 and level-3 jump is the highest-leverage gold in nuclear defense: it does not just raise the ceiling of the range, it moves the SAM into the radius where the crown and the core are simultaneously interceptable, and a SAM that can intercept both your two most expensive landings is the SAM that makes the 70-tile buffer a tool you control instead of a trap the enemy sets. The detection window of 600 tiles is wide enough that you will almost always see the launch, which is what makes the placement fixable in real time: the launch is visible, the landing point is computable, and the SAM that should own that landing is a placement decision you can still make while the missile is climbing, which is the whole argument for keeping one launcher unbuilt and movable in the endgame.

Failures, counters, and the mode and map adjustments

The failure modes are the ones to recognize on your screen before you waste gold on the wrong fix. The first is the SAM that tracks and intercepts a small missile while a large one keeps climbing, which is the distance bonus working as designed, and the fix is a second SAM toward the expensive landing, not an upgrade on the engaged one. The second is the SAM that fires at the first warhead of a MIRV and then sits idle while the rest land, which is the 90-tick cooldown, and the fix is more SAMs or fewer enemy warheads per wave, because no placement rescues a one-shot defense against five warheads. The third is the SAM that never fires at all on a distant launch, which is the detection or range gate, and the fix is a level upgrade or a closer placement, because a SAM outside the firing range of the interception point is scoring targets it is not allowed to shoot. The fourth is the player who spends the whole defense on level upgrades and is left with a single high-level SAM whose 90-tick window cannot cover two simultaneous landings, which is the reverse failure, and the fix is the SAM launcher guide’s count-versus-level curve, which says the extra SAM is usually the better first buy. The counterplay on the attacker side is symmetric and worth knowing because it is how you should be reading your own launches: to get your hydrogen through, land it more than 70 Manhattan tiles further from the enemy’s SAM than the atom you send as the decoy, and if the enemy has moved a SAM toward your crown to fix that, your decoy is now the closer landing from the second SAM’s position and you are back at the tie, which is why the attack is a placement race against their placement, not a one-shot trick. Mode and map shift the whole thing: on coastal maps your crown is closer to the sea wall and the landing grid is shorter, which shrinks the distance-bonus spread and makes the hydrogen’s type bonus worth more of the score, so the hydrogen is easier to protect and harder to slip through; on large open maps the landing points spread wider, the distance bonuses diverge faster, and the 70-tile buffer is the number that decides more races; in the overtime endgame where both players are at their MIRV budget, the nuclear stalemate breaker timing is what decides which landing points are live at all, and the nuke defense protocol window is the second-order timing on top of the first-order targeting this page covers.