Rules

Knights Archers Zombies — rules

Four heroes hold one gate against a rising horde, and a single mistake ends the wave for everybody.

The board

A fixed 1235 × 659 arena (mapPath: "arena"), 24 ticks per second. The dead walk in at the breach on the east edge (x = 1178) and march west toward the gate on the west edge (x = 40). Both are baked into the floor art, so the geometry of the game is legible with the HUD off.

The seats

num_agents is 4. One seat drives exactly one hero.

There is no friendly fire: arrows pass through heroes.

The horde

Zombies enter on a ramping schedule — 0.29/s at the start of a wave rising to 1.20/s after 80 s, about 79 zombies over a full wave, never more than 40 alive at once. Each has 2 hit points and walks at 36 px/s down a flow field toward the gate. A zombie with a living hero inside 90 px stops marching and charges it. Zombies do not collide with each other.

Losing

The wave ends the instant:

1. a zombie's centre reaches x <= 40 — a breach; or
2. a zombie's centre comes within 26 px of any living hero — a casualty.

There are no respawns, no second chances, and no hit-point pool: hitPoints 1, lives 1. A hero who is not you dying ends your wave too.

Winning

An episode is two waves of 2304 ticks (96 s). Surviving a whole wave clears it.

kills      = every zombie the four of you killed, over the episode
cleared    = waves that ran their full 96 s with the line intact (0, 1 or 2)
teamValue  = kills + 20 * cleared
teamScore  = min(teamValue, 180) / 180                 -- the same for ALL FOUR
credit[s]  = 0.004 * kills[s] / max(1, kills)          -- the tie-break only
scores[s]  = teamScore + credit[s]
win[s]     = teamScore >= 0.5

Everybody's score is the same score. The personal credit range (0.004) is smaller than one extra team kill (1/180 = 0.005556), so killing more than your share is worth nothing if the line breaks.

The published scripted baselines

Both emit the same directive object an LLM does, on the same 4.0 s cadence. They are published so that "cooperating with a partner you did not write" here means "a partner whose rules you know".

• phalanx — the certification player, the per-turn fallback, the driver of a seat that never connects, and the default. It ranks the live zombies by gate distance and divides them so two seats never duplicate work: KNIGHT-alpha intercepts the leader, KNIGHT-beta the second, ARCHER-alpha focuses the leader and ARCHER-beta the third. An archer with anything inside 150 px falls back toward the gate for a turn; a knight with four bodies inside 90 px gives 140 px of ground for a turn. With no zombies alive everybody holds the choke — knights at [560, 240] and [560, 420], archers at [300, 240] and [300, 420].
• stand — deliberately weaker and different in shape: every hero holds its choke post for the whole wave and never moves. It kills whatever walks into reach and leaks everything that walks around it.

tools/tune_baselines.nim is the grid harness that chose phalanx's three numbers; tools/tune_baselines --check re-plays them in CI.

Orders

Every 4 seconds each seat issues ONE order for its own hero and a deterministic controller executes it for the next 4 seconds. See COMMANDING.md for the schema and PROTOCOL.md for the wire.