Survival mechanic — not covered elsewhere

Heat and Cold

Two environmental hazards, two different questions — the cold asks whether you prepared, the heat asks whether you can keep moving

Two specific biomes carry a real, damaging environmental hazard on top of whatever creatures live there. According to the development log, both were deliberately built to ask a different question of the player rather than being the same underlying timer reused with a new coat of paint — one is answered before you ever set out, the other is answered by what you're doing right now.

Cold: the Snow and Alaska biomes — did you prepare?

Standing in the Snow or Alaska biomes starts a twelve-second grace period before the cold begins to bite — after that, it deals damage equal to 4% of your maximum health every three seconds for as long as you're still exposed. The only thing that matters is whether you own a Lantern: simply having one in your inventory grants complete immunity, checked the moment you're bitten rather than something you have to actively use, and it works identically whether it's day or night. An earlier version of this check asked whether a lit lantern was actually visible in your hand instead — which only exists at night in this game — so during the day the game would have told a player to light a lantern it would then refuse to let them hold. Checking ownership instead of the visible flame fixed a hazard whose own instruction was false half the time.

Heat: Hell, and Hell alone — can you keep moving?

Hell carries the opposite kind of hazard, and no item in the game protects against it. A heat meter rises by 4 points a second while you stand still (about 25 seconds to fill) and drains by 12 points a second the moment you move at all — anything above roughly 2.5 units per second counts as moving. Once the meter reaches its cap, it bites for 4% of your maximum health every two seconds until you cool back down. The desert biome was deliberately considered and rejected as a second heat zone: the desert already has its own gameplay reason to stand still there, and a hazard that punishes standing still would have quietly broken it. Hell has no such reason, so nothing is taken away by adding the hazard there.

The heat meter freezes completely while any menu or panel is open, specifically so that checking your own inventory in Hell doesn't kill you for the crime of using the interface — and it's also suspended while flying, inside a home, casino, chapel, or other building, or on the Moon, since none of those are really "in Hell" even if the coordinates say otherwise.

Version history

• v1119 — a real on-screen readout, for the first time. Neither hazard had ever shown up anywhere on screen before this — a player learned they were overheating or freezing purely from the damage numbers themselves. A small HUD status stack now shows heat and cold by name with a percentage or timer whenever either is actually active, alongside the same treatment for Prion Madness.

Trivia

• Both hazards were deliberately kept as two entirely separate systems rather than one shared "biome hazard" counter, on the reasoning that three hazards sharing one counter would really just be one hazard wearing three skins — a second hazard was only added once its own mechanic asked something genuinely different of the player.
• The design notes explicitly name three other places that could plausibly carry a similar hazard — the deathzone, the nuclear wasteland, and the general concept of more of them — and just as explicitly leave them unbuilt, rather than padding the system out for its own sake.