The rules of ExPilot as one pure value, run by Cauldron2D.World.

Ships turn, thrust, fire and shield on held actions — thrust as hard as the input's strength says, its exhaust as long; gravity from the map and its points pulls on them; a wall bounces a ship, at a cost in fuel, unless the ship hits it unshielded faster than @wall_crash_speed, which is a crash; fuel stations refill a ship near them; wormholes move a ship elsewhere; cannons on the map fire at ships in front of them; a shot kills an unshielded ship it meets unless armour takes it; two ships that meet crash unless shielded, and shielded ships bounce apart. A ship whose tank has been empty for ten seconds, flying or sitting on its base, is lost as if it had crashed. A dead ship comes back on its base a few seconds later. Watchers join with spectate: true and see the arena without a ship.

A player without a base to join takes a robot's: the robot's ship is removed and the player seated there. A player joining without a team goes to the team with fewer ships.

Map rules

The map's header sets the rules ExPilot.Map.option/2 reads: allowshields, initialfuel and the initial… kit every ship spawns with, shotswallbounce, shotsgravity, friction, allowplayerkilling, allowplayercrashes and allowplayerbounces, playerwallbouncebrakefactor, targetkillteam (a team whose last target falls is destroyed) and treasurekillteam (a team whose ball is scored against is destroyed), dropitemonkillprob, laserisstungun, minefusetime, firerepeatrate, shieldeditempickup, shieldedmining, ballswallbounce, checkpointradius, playersonradar, and gravity's gravityangle or, with gravitypointsource, a pull toward gravitypoint.

Items appear on the map (ExPilot.Items) and are used with keys (ExPilot.Gear); missiles, mines and lasers are ExPilot.Weapons. With teamplay, teammates' shots pass through each other when the map has teamimmunity, team scores add up, targets (ExPilot.Targets) and balls in treasures (ExPilot.Ball) score for a team. With racemode, ships pass the checkpoints in order (ExPilot.Race). What happens is told in messages the view carries.

Actions

:turn_left, :turn_right, :thrust, :fire, :shield, then the item keys of ExPilot.Gear.actions/0. An aim in the input turns the ship toward that world point instead of the turn keys. :next_watch, pressed by a player who is out or by a watcher, moves the view to the next ship flying, by name; the view's watching names it.

Events

Every event carries a position: {:fire, pos}, {:explosion, pos}, {:bounce, pos}, {:shot_wall, pos}, {:refuel, pos}, {:wormhole, pos}, {:cannon, pos}, {:respawn, pos}, {:kill, pos}, {:round, pos}, {:pick_up, pos}, {:missile, pos}, {:mine, pos}, {:laser, pos}, {:cloak, pos}, {:ecm, pos}, {:transporter, pos}, {:hyperjump, pos}, {:target_hit, pos}, {:target_destroyed, pos}, {:goal, pos}, {:checkpoint, pos}, {:finish, pos}.

Rounds

A ship on its base sits still until it thrusts, and for three seconds after it appears there — on joining, on respawning and at a new round — nothing can hit it; it shows its shield meanwhile. With limited lives, a ship whose lives are gone stays out until the round ends: when one ship (one team, with teamplay) is left standing among two or more, it is told it won and round_over_in counts down four seconds; then, or at once when nobody is left, a new round starts and everyone is back on their base with their lives, scores kept.