v1.0.0-alpha.13 is where the boss work starts to take shape. Last release added mobs that fly; this one adds the two big pieces those aerial bosses — and everything else on the roster — were waiting on: multi-part “segmented” boss bodies and mobs that burrow through solid terrain. There’s also another sweep of the mod config format to keep everything consistent, and a round of fixes on top.

Existing worlds and saves carry over as-is — no reset this time. There are breaking changes to a handful of config keys (detailed below), but since the game is still pre-mods there’s no known impact.

Bosses, taking shape

Two features here are the foundation for the set-piece fights we’ve been designing:

• Segmented bosses. A boss can now be made of many linked parts — a controller plus a train of body segments — that move and fight as one creature under a single shared health bar. The first thing it makes possible is a proper worm boss: a long body that trails behind its head, where every segment can be hit but damage pools to the whole creature. Parts can trail in a chain, sit in a fixed cluster around the boss, or be driven entirely by a fight’s own script.
• Burrowing mobs. A mob can now move through solid terrain — tunneling straight toward its target through rock instead of walking around it, holding its position underground, and surfacing where it likes. It still collides with creatures, so it can’t pass through you. Combined with the segmented bodies above, this gives us the diving-and-surfacing worm you’d expect, and it works on any mob, not just bosses.

Neither is something you’ll stumble on in normal exploration yet — they’re the engine groundwork, and the bosses that use them are still in the workshop. But together with flying from last release, the toolkit for the 1.0 boss roster is nearly complete.

For modders: scripting big fights

Alongside the boss features, the server-side scripting API for creatures got the handles a fight needs. A script can now spawn a mob and keep a handle to it — then name it, move it, teleport it, and deal damage directly from one entity to another, rather than routing everything through area-effect zones. Entities can report their id, type, and position, and a boss made of parts can reach its own segments (or a segment its controller). It’s enough to script adds, phase transitions, and coordinated multi-part attacks. Full details are in the modding docs.

The config cleanup continues

The consistency pass across the mod config format — the through-line of the last several releases — keeps going. The theme is unchanged: the same idea should have the same name and shape in every file, and a mistake should tell you so at load. The notable ones this round:

• One name for “how high.” Every field that means an absolute vertical position now spells it altitude (min-altitude / max-altitude) — biome bounds, flat-world layers, world generation pools, and particle emitters previously scattered across height, depth, and y-spawn. (Thickness measured down from the surface keeps its own name, since it’s a different thing.) A biome’s height bounds also actually apply now — they were being silently rejected before.
• Casing no longer bites. Config enum values are matched case-insensitively everywhere now — sfx or SFX, ring or Ring, and so on — so a capitalized value copied from an example can’t silently fail to load. Notably, a mob’s type is now matched case-insensitively against the server’s spawn limits; it was the last case-sensitive value in the whole schema, and a casing mismatch used to quietly stop a mob from ever spawning.
• A batch of key renames for parallelism. Among them: a projectile launcher’s fire-delay-ms is now fire-cooldown-ms (it’s the minimum time between shots), max-oxygen-level is now max-oxygen to match max-health, block drag keys are drag-up / drag-down to match their left/right siblings, and block texture animations use a loop: true|false flag like the UI does instead of a separate loop/once mode. Mob render settings also moved out to the top of a mob entry, matching every other config.
• Friendlier shorthand. A drop table now takes an item as either a bare name or a full block, matching loot tables; an item that summons a creature accepts a bare creature name; and a 2D velocity can set just one axis and leave the other at its default, on mobs and players alike.
• Biome weather odds are a weight, not a chance. The value was always a relative weight (sunny: 3 / rainy: 1 means 75/25), never a percentage — so it’s now named for what it is, including where scripts read it.

Modders updating configs should skim the changelog for the full rename list; a few of these drop the old spelling entirely.

Typos keep failing loudly

The “a misspelled field tells you instead of vanishing” guarantee reached the last places it hadn’t. A mistyped script-hook name — the classic server-udpate for server-update — now fails the entry with a named error in every config that has hooks (mounts, interactables, blocks, players, items), instead of leaving the hook silently unwired. Unknown keys inside a few remaining nested blocks (summon info, held-item data, drop-table entries) are caught the same way. And particle textures no longer demand dimension fields they never actually used, so a particle can’t fail to load over a value that did nothing. The modding docs got a matching accuracy pass — corrected reference tables, the server connection-limits settings written up, and stale “this is parsed loosely” caveats brought in line with how strict things now actually are.

Fixes you’ll feel

• HUD icons are back. The health and oxygen icons at the top of the screen had silently stopped drawing after an internal rename; they render again.
• Boss health bars stick around. A boss that flew or wandered out of view and came back used to lose its health bar for the rest of the fight — it now reappears correctly every time.
• No more silent spawn failures for scripts. A script spawning a mob with a mistyped name or into a missing world now logs why instead of failing invisibly.

What’s next

alpha.13 is a groundwork release: segmented bodies and burrowing turn the boss designs on paper into things the engine can actually run, and the scripting API gives a fight the controls it needs — while the config cleanup keeps closing the gap between “what the docs say” and “what the game does.” The next stretch is where those bosses start coming together for real. Thanks as always to everyone playtesting with us; keep the reports coming.