What it is
Sealed arenas are square rooms with impenetrable walls used for mini-boss and boss encounters. When the player enters one of these levels, the room materializes at full size around the player, the biome terrain inside is stripped away, and four solid walls block the player, projectiles, and knockback effects from leaving. The fight ends when the boss dies; the walls drop on victory or when the run ends on player death. There is no time limit and no escape — the only outcomes are kill the boss or die.
Stats / variables tables
Arena dimensions
| Field | Value | Notes |
|---|---|---|
| Shape | square (rect) | Sealed arenas are always rect; circular rooms exist only on the legacy non-sealed path |
| Half-extent | 1400 world units | Distance from center to each wall face |
| Full side length | 2800 world units | 2 × half-extent |
| Total play area | 7,840,000 world units² | Side length squared |
| Wall thickness | 2000 world units | Each wall is a cuboid this thick along its short axis |
| Wall length (per side) | 3400 world units | Half-extent + wall thickness, extending past corners on both ends |
| Corner overlap | 2000 world units | Each wall overlaps the perpendicular walls by the wall thickness so diagonal knockback cannot squeeze through |
| Initial size on spawn | full (2800 × 2800) | Sealed arenas appear at final size instantly; they do not shrink or expand |
| Center anchor | player position at spawn | Room is built around the ship so the player never appears clipping a wall |
| Player spawn (within arena) | arena center (0, 0) | Ship is placed at the room’s center on level start |
Terrain handling inside the arena
| Field | Value | Notes |
|---|---|---|
| Biome terrain inside footprint | despawned on entry | All terrain pieces whose centroid sits inside the arena are removed |
| Cull radius | 1540 world units | Half-extent × 1.1 — slightly oversized so pieces straddling the wall do not leave fragments clipping inside |
| Floaters inside footprint | despawned on entry | Floating biome props are removed by the same cull |
| Terrain regenerated after teardown | yes | Terrain chunk index is rebuilt after the cull |
| Inner terrain replacement | none by default | Some bosses overlay their own terrain layouts (e.g. pillar rings, hazard pads) — see the bosses gameplay page |
Time limits and escape rules
| Field | Value |
|---|---|
| Time limit | none |
| Soft timer | none |
| Escape mechanic | none — walls are permanent until boss death |
| Player exit on victory | walls drop, the level advances to the next room |
| Player exit on defeat | run ends; walls are torn down with the rest of the encounter |
| Pausing | standard pause behaviour; arena state is preserved |
Rewards and level cadence (normal mode, 5 levels)
| Level | Kind | Sealed arena? | End condition |
|---|---|---|---|
| 1 | normal | no | 4-minute biome timer |
| 2 | normal | no | 4-minute biome timer |
| 3 | mini_boss | yes | mini-boss death |
| 4 | hard | no | biome timer (ramp pinned, basics-only window skipped) |
| 5 | boss | yes | final boss death → results screen |
Rewards and level cadence (Challenge Mode, 10 levels)
| Level | Kind | Sealed arena? | End condition |
|---|---|---|---|
| 1 | normal | no | biome timer |
| 2 | normal | no | biome timer |
| 3 | mini_boss | yes | mini-boss death |
| 4 | normal | no | biome timer |
| 5 | normal | no | biome timer |
| 6 | mini_boss | yes | mini-boss death |
| 7 | hard | no | biome timer |
| 8 | hard | no | biome timer |
| 9 | mini_boss | yes | mini-boss death |
| 10 | boss | yes | final boss death → results screen |
Challenge Mode unlocks per-planet after clearing the final boss in normal mode. Rewards for the whole run are doubled at run-assembly time.
Reward attribution
| Reward | Source | Notes |
|---|---|---|
| Boss XP / currency / pickup cascade | the bosses gameplay page | The arena itself awards nothing; all payouts come from the boss kill |
| Reward picks | end-of-level flow | The same end-of-level reward flow runs after a sealed arena clears |
Boss difficulty scaling within sealed arenas
| Tier | HP multiplier | Damage multiplier |
|---|---|---|
| Mini-boss | 4.0× | 4.0× |
| Boss | 8.0× | 8.0× |
A depth scaling factor (×1.0 to ×1.5) is applied on top, based on the player’s current level relative to the run’s final level. The boss tier’s multiplier is exactly 2× the mini-boss tier so the relative scale is preserved.
Spatial helper queries (used by abilities, AI, spawn placement)
Sealed arenas expose a fixed set of spatial query helpers so abilities and AI never reference screen size or world coordinates directly.
| Helper | Returns |
|---|---|
| contains(x, y) | True if the point is inside the current arena footprint |
| clampPoint(x, y, margin) | The nearest point inside the arena minus a margin (default margin 20 world units) |
| randomPoint(margin) | A uniform random point inside the target footprint, minus a margin |
| cardinalPoints(fracOfRadius) | The four compass-direction points (N, E, S, W) at the given fraction of half-extent |
| ringPoints(count, fracOfRadius) | count evenly spaced points on a ring at the given fraction of half-extent |
| edgePoints(count) | count evenly spaced points along the perimeter (parametric walk for rect) |
| oppositePlayer(playerX, playerY, dist) | The point on the line through the arena center opposite the player, at dist from center, clamped inside |
| radius() | Half-extent (1400) — for rect arenas this is min(W, H) / 2 |
| diagonal() | The arena’s diagonal length |
| bounds() | The axis-aligned bounding box (minX, minY, maxX, maxY) |
| Default margin | 20 world units |
How it works
Sealing trigger — when a level kind of mini_boss or boss starts, the engine spawns a sealed arena centered on the player’s current position. The room is built directly in its final locked state; it does not animate in.
Construction order — first the biome terrain and floaters whose centroids sit inside the arena footprint are despawned (using a 1.1× oversized cull so partial pieces near the wall do not leave fragments clipping inside). Then the room is registered as a rect-shaped locked room at full size. Then four physics walls are created — one along each side, each 2000 world units thick, each extended past the corners so that the overlap blocks diagonal escape paths. The player’s physics body is teleported (velocity preserved) to the arena center if it is not already there, and any stray enemy or boss bodies from previous frames are dropped. Finally a sealed-arena-active flag is set so other systems know the arena is up.
The fight — the boss spawns according to its roster; spawn positions come from the spatial helpers above (cardinal points, ring points, edge points, opposite-player). Abilities, AI movement, and projectile lifetimes all route through the same helpers and clamp to the arena bounds. The player is held inside by three independent layers running in parallel: a per-frame ship clamp, the four physics wall colliders, and the visible wall thickness.
Unseal on victory — when the boss dies, the level-advance flow tears down the arena: the physics walls are removed, the sealed-arena-active flag is cleared, and the room and arena helper are dropped. The end-of-level reward flow then runs as normal and the next level begins. Calling teardown when no arena is active is a safe no-op.
Player death — the arena is torn down by the same path as part of the encounter cleanup; the run ends and returns to the results / metagame surface.
Interactions
- Bosses — sealed arenas are the only surface in which boss and mini-boss encounters are run. Spawn positions, ability targeting, leash checks, and culling all use the arena spatial helpers.
- Physics — the four walls are static Rapier cuboid colliders. They are added on sealing and removed on teardown. They are independent of the visual representation.
- Per-frame ship clamp — even with physics off (or before physics is ready) the ship is clamped each frame to the current room bounds, so the player can never leave even on a degraded physics path.
- Terrain and floaters — biome pieces inside the footprint are removed on entry and not restored on exit (the next level rebuilds its own biome).
- Enemy / boss bodies — any stray enemy or boss physics bodies are cleared during sealing so the new fight starts clean.
- Affixes and abilities — every boss affix and ability that places points in space goes through the arena helpers, so they automatically respect the arena’s size and shape.
- Level progression — appears at the level cadence above. Sealed arenas are gated by level kind (
mini_boss,boss); other kinds (normal,hard) never seal. - Biome / preset visuals — the biome preset still drives palette, illumination, and overall visual tone for the level, but its terrain pattern (hubs, spokes, density, ring radius, block size, terrain type) does not appear inside the sealed footprint because that terrain is despawned.
What it does NOT do
- Sealed arenas do not shrink, grow, or move once spawned. They appear at full size and stay there until torn down.
- Sealed arenas do not use a closing animation, a countdown, or a warning telegraph before sealing.
- Sealed arenas do not have a time limit; there is no enrage timer driven by the arena itself (individual bosses may have their own internal timers — see the bosses gameplay page).
- Sealed arenas do not have an escape mechanic. Walls cannot be broken, jumped over, dashed through, or destroyed.
- Sealed arenas do not award XP, currency, or pickups directly; all payouts come from the boss kill.
- Sealed arenas do not regenerate the biome terrain that was stripped on entry.
- Sealed arenas do not appear on
normalorhardlevels. - Sealed arenas do not use circular geometry; only the legacy non-sealed boss room path can be circular.
- Sealed arenas do not move with the player. The center is fixed at the player’s position on spawn.
- Sealed arenas do not scale their size with planet, biome, depth, or boss tier — every sealed arena is 2800 × 2800 world units.
- Sealed arenas do not stack. There is at most one active sealed arena at a time.