Room rules | Citadel docs

world.rules{ fall = true }

landings past three blocks cost health

world.rules{ damage = true }

the world hurts: void, fire, lava, drowning, suffocation, cactus

world.rules{ hunger = true }

the food bar runs down and, when full, heals

world.rules{ anticheat = false }

on by default: moves and hits are checked for cheats, see below

world.rules{ day_cycle = true }

the sun moves: see "the time of day"

world.rules{ redstone = false }

on by default: redstone signals move, see below

world.rules{ survival = true }

the whole game: see below

world.rules()

{ survival = false, fall = true, damage = false, hunger = false, anticheat = true, day_cycle = false, redstone = true }

room.world.rules{ fall = true, damage = true }

per room; a room made by rooms.create starts with only the anticheat and redstone on

A mode: full server has them all on. A pack can turn one off.

A rule is true or false. A rule that you leave out keeps its value, and so does a rule you write as nil. Any other value is an error: world.rules{ fall = 0 } and world.rules{ fall = "off" } stop the script.

redstone is on in every room until a pack turns it off. With it off, no signal moves: a lever lights no wire, a piston stays in, a pack block’s power gives nothing and block.powered reads false. What was lit when the rule changed stays as it is until something beside it changes.

anticheat checks what each Java player’s client claims:

A player who flies, runs too fast, sends moves faster than the game ticks, or walks through full blocks goes back to the last legal position.
A claim to stand on nothing does not prevent fall damage.
A hit on something the player does not look at, or faster than 20 per second, does not land.
After enough failed checks in a short time, the engine removes the player. The message names the check.
The flight check skips creative and spectator players, a player who may fly (player.can_fly), a rider and a dead player.
player:push and a movement effect (speed, jump_boost, levitation, slow_falling, dolphins_grace) exempt the player while they last. player:teleport is always allowed.
A pack that moves players in any other way turns anticheat off: world.rules{ anticheat = false }.

survival gives the room to the engine’s survival, as on a mode: full server:

A broken block drops its normal drops.
A block the world breaks by itself drops them too: a torch whose wall is gone, a leaf that decays, a block an explosion or a piston breaks, sand that cannot land.
Placing uses up the stack.
The inventory and a crafting table craft.
A death drops the inventory, and the respawn button works.
The engine saves the player’s inventory.
It also turns on fall, damage, hunger, anticheat and day_cycle.

Without survival, a dig reaches no block, and a block the world breaks by itself leaves no item. game.block(name).drops = true switches one block of the game back on (see “Blocks”). A pack block still leaves the drops its definition lists; drops = "table" is the game’s own drop and leaves nothing. A survival pack puts world.rules{ survival = true } at the top, and runs the same on either kind of server.

Anything that is not a rule is the pack’s job: player:damage for a hit, player.health to heal, players.on_death and players.on_respawn for what happens next, and hit.player in players.on_click for one player hitting another:

world.rules{ fall = true }
players.on_click(function(player, hit)
    if hit.button == "left" and hit.player then
        hit.player:damage(2)
        hit.player:push(player:look() * 0.5 + vec3(0, 0.3, 0))
    end
end)