game.sim.Battle

The Kessrel Line battle, as data. Three thousand human line troopers in ten regiments hold a fortified canyon against waves of Vesh — thousands alive at once — for seven waves, while the last ship loads at the Gate of Harrow behind them.

Nothing in here is an entity and nothing is physics. The whole field is one flat unit table (game.sim.units) that the crowd renderer reads, and the rules run over regiment blocks and alien packs at a fixed fifteen-hertz tick.

The scene entrypoint puts this on mount_sim. It takes no fields but one:

entity.find("mount_sim").component.get("game.sim.Battle"):setField("debugDraw", true)

What it simulates

Regiments. Ten blocks of three hundred, thirty across and ten deep. A block carries a count, a morale, a stance and a post; its soldiers are the first count slots of its range, ordered front rank first, so a regiment that loses men empties from the rear the way a real formation steps up.

Packs. The Vesh arrive as packs — forty skitters, ten brutes, one titan — each owning one contiguous block of its caste's index range. A pack has a centroid, a heading, a hit-point pool and a fixed scatter arrangement chosen from eight per caste, so a hundred packs are not a hundred copies of one clump. Unit positions are the centroid plus that scatter rotated by the pack's heading; no per-unit steering runs at all.

Movement. Far from its target a pack is carried down the canyon by the canyon; close in it hunts (FUNNEL_NEAR / FUNNEL_FAR). Packs of a caste push off each other over a coarse spatial grid so the tide spreads rather than stacking, and the canyon walls (K.halfWidthAt) hold it in.

Fire. A regiment concentrates on the three nearest packs inside its range AND its arc, in a 58 / 26 / 16 split, at triple weight inside its close band. The arc is why where a regiment stands decides what it can answer, and the close band is why holding a line is worth more than spreading thin.

Melee, morale, breaking. A pack in contact kills soldiers; losses and time in contact drain morale; under K.BREAK_MORALE a regiment breaks, turns south and runs, and the tide stops chasing it — the hole it leaves is what costs the Gate. A broken regiment recovers slowly on its own and instantly under Rally, then marches back to its post.

Mines. A posted sapper regiment lays an arc of fourteen mines ahead of itself after holding for three seconds. A pack that crosses one sets it off.

Abilities. cmd.ability fires Orbital Lance (a delayed strike that clears a crater), Mortar Barrage (five walking shells) and Rally (the selection's morale back to full). Each reports fired, impact and ready on battle.ability.

The Gate and the endings. Aliens within ten metres of the Gate face chew its hit points down. Zero is defeat; no regiment left standing is defeat; the seventh wave clearing is victory. Each emits game.end and sets the ending phase.

The bus

Reads cmd.move, cmd.stance, cmd.ability; starts on game.battle and resets on game.restart. Emits battle.wave, battle.waveEnd, battle.regiment, battle.gate, battle.ability, battle.kills, battle.titan, game.end, and battle.mine { x, z } — the one event this slice adds beyond the list in game.shared. It writes K.battle every tick, including fireIntensity and meleeIntensity for the sound bed, and speaks its lines through K.say.

Cost

The rule tick and the per-unit pass are measured and readable at runtime:

entity.find("mount_sim").component.get("game.sim.Battle"):stats()

Against a 4 ms budget, with the unit table full (9,825 live records, 271 packs): rule tick 1.2 ms average and 2.3 ms peak, per-frame work 1.6 ms average and 3.1 ms peak. At a played wave 7 (3,400 aliens): tick 0.97 ms, frame 1.5 ms.

That holds because the rules run over ~280 packs and 10 regiments rather than over 10,608 units; the per-unit work is four writef32 calls and six multiplies, sharded across three frames; and the whole 339 KB table goes to the GPU in one writeBytes costing 0.06 ms.

The test surface

debugForceWave(n), debugEndWaveNow(), debugClearField(), debugFillField(), debugPushTide(z), debugHurtGate(hp), debugHurtRegiment(n, id?), debugHurtMorale(amount, id?) and resetStats() exist so the endings and the late waves are provable in seconds rather than in the eight minutes a played battle takes. Nothing in the game calls them.