Rules

Rules

An 11 × 11 walled grid. Four bombers, two teams of two. Bombs, wooden walls, three power-ups and two collapsing rings. x is the column 0..10 left→right, y is the row 0..10 top→bottom.

Seats, teams, corners, aliases

Teams are fixed by slot parity and assigned by the server, never chosen by a policy.

Partners sit on a diagonal. The map is 4-fold rotationally symmetric about (5,5), so every corner's surroundings are an exact rotation of every other's: no seat has a positional advantage, and no side-swap game is needed. One game per episode.

The board

• The outer ring (x == 0 or x == 10 or y == 0 or y == 10) is rigid wall — 40 cells.
• The interior cells with both coordinates even are rigid too — the classic Bomberman lattice, 16 cells. It guarantees the board is connected by construction: every odd row and every odd column is fully open, and those form a spanning grid, so there is no repair pass.
• The four corner cells and their two interior orthogonal neighbours each — 12 cells — and the centre (5,5) are always passage.
• The remaining 52 cells are 13 rotation orbits of four. A xorshift64* seeded by the episode seed shuffles them; the first 9 orbits are wooden wall (36 cells) and the last 4 are passage. Of the 9 wood orbits, orbits 1–2 hide an extra bomb, 3–4 hide +1 range, 5 hides kick and 6–9 hide nothing: 20 power-ups, upstream's NUM_ITEMS.

Totals at tick 0: 56 rigid, 36 wood, 29 passage. One living bomber per cell; at most one bomb per cell; at most one loose power-up per cell.

The bomber

alive, x, y, ammo (start 1, cap 5), range (start 2, cap 6), kick (start false). A bomber has no hit points: a flame kills instantly.

Bombs

fuse 8 at placement, range copied from the placer and never updated, an owner, and a velocity (none|up|down|left|right). A bomb laid at tick t detonates at tick t + 8.

A detonation's blast cells are its own cell plus, in each of the four directions, up to range − 1 cells: walking outward, stopping before the first rigid cell, stopping at and including the first wood cell, and passing through passage, power-ups, bombers and bombs.

Chain reaction: any bomb standing in a blast cell detonates in the same tick, to a fixpoint.

Flame is a cell timer of 2 ticks set at detonation and decremented at the end of every tick, so a flame is lethal on the tick it appears and on the one after it.

Power-ups

extrabomb (ammo += 1, capped), incrrange (range += 1, capped), kick (idempotent). Picked up by stepping onto the cell; consumed. Wood destroyed by a blast reveals the power-up it was hiding onto that cell (it survives the blast that revealed it); a power-up already lying in a blast cell is destroyed.

Turns and ticks

A tick is one Pommerman step. A command turn is one order round, every turnTicks = 4 ticks, beginning immediately before tick 1. maxTicks = 144 ⇒ 36 command turns.

Per command turn T, in this order:

1. The engine snapshots the world and builds all four seats' observations.
2. Radio delivery — each seat's observation carries the pair its partner sent with its turn T−1 order (null on turn 1). Exactly one turn late, always, including when the partner fell back. The opposing team's pairs are never in any observation.
3. All four seats' LLM requests go out as one parallel batch, attempt-1 deadline 12 s.
4. Every seat that timed out, errored or returned nothing usable is retried once, again as one batch, 5 s.
5. A seat still without a usable reply gets the sapper scripted order and a fallback record.
6. Orders are installed. A seat that names no order keeps last turn's; an invalid field is repaired, never dropped, and counted in ordersRejected.
7. say (≤ 100 runes) and the accepted order become replay records; notes (≤ 200 runes) is echoed back to that seat only; the radio pair is stored for turn T+1.

Then, for each of the next four ticks, in this order — this is the whole physics and nothing else mutates the world:

1. tick += 1. Snapshot.
2. Collapse. If this is a collapse tick, every cell of that ring becomes rigid; a living bomber there dies crushed, a bomb there is removed without detonating, a power-up there is destroyed, a flame there clears. First, so nothing else acts on a cell about to be wall.
3. Choose one action per living bomber, ascending seat, from the snapshot.
4. Bomb placement, ascending seat. A bomber whose action is bomb places one iff ammo > 0 and no bomb is on its cell; otherwise the action degrades to stay. A bomber that places a bomb does not move this tick.
5. Kicked-bomb movement, ascending bomb id. A moving bomb advances one cell iff the destination is passage and holds no bomb, no living bomber and no flame; otherwise it stops.
6. Bomber movement, ascending seat, from the snapshot positions: rigid or wood → the move fails; a bomb in the way → kick it iff the mover has kick and the cell one further is clear (and the kicker does not move), else the move fails; a cell holding a bomber, or already taken this tick → the move fails (no swaps, and two bombers for one empty cell resolve lower seat wins); otherwise it moves and picks up whatever is there.
7. Fuse tick. Every bomb laid before this tick, fuse -= 1.
8. Detonation, with chain reaction, to a fixpoint.
9. Flames and wood. Blast cells become flame; wood becomes passage and is credited to the owning team of the lowest-id bomb covering it; every detonated bomb is removed and its owner regains one ammo (capped).
10. Deaths, simultaneous. Every living bomber on a flame cell dies, all at once — mutual annihilation is a real outcome. cause ∈ {bomb, suicide, friendlyfire, crushed}, and kills increments only for a victim on the other team.
11. Flame decay.
12. The tick is mixed into gameHash.
13. The end conditions are evaluated.

Collapse

ring(x,y) = min(x, y, 10−x, 10−y). Ring 0 is the permanent border. At tick 96 every cell of ring 1 becomes rigid; at tick 120 ring 2 goes. Play ends inside the 5 × 5 block x,y ∈ [3,7]. (The blitz variant collapses at 64 and 80 on a 96-tick clock.)

Orders

The survival override runs ahead of the order. If the bomber's own cell is dangerous within the dodge horizon (8 ticks), the controller ignores the order and takes the first step of the shortest path to a cell safe for the whole horizon. It is not a shield: a bomber boxed into a dead end still dies, which is exactly how Pommerman is won.

"An escape exists" means: after hypothetically placing the bomb, the same escape search finds a safe cell. This is the one place the controller refuses a commander's order.

Ending and scoring

The game ends at the first of: team wipe (endRule: wipe; both teams at once is a draw), the tick cap (tickCap, settled by living-bomber count), the engine's wall-clock stop (wallClock, results.reason: deadline) or a fault.

outcome[t]   = +1 / 0 / -1 by living bombers
teamScore[t] = 100 * outcome[t] + 20 * (alive[t] - alive[other]) + (wood[t] - wood[other])
score[seat]  = teamScore[team(seat)]

Range ±176. Higher is better. The four seat scores sum to exactly zero.