Fire a projectile. The action on the game varies greatly depending on the mechanics of the projectile being fired.
weapon: change field weapon: vertical field: spike field: rotate on pressed: jump on pressed: shoot on got item: power up
weapon: chase on pressed: shoot on holding: move
on pressed: flap on pressed: shoot field: roughness field: spike rule: time limit
weapon: artillery on pressed: shoot on holding: thrust rule: chain
weapon: smoke weapon: auto aiming weapon: ray on pressed: shoot
weapon: blow off weapon: explosion obstacle: well up on pressed: shoot on pressed: attack
on pressed: turn on pressed: shoot
player: inverted on pressed: shoot weapon: ray field: outpost
rule: control weapons obstacle: split on holding: rotate on pressed: shoot player: multiple field: outpost
on pressed: shoot on holding: shoot on pressed: turn
weapon: auto aiming weapon: explosion field: outpost on pressed: shoot
weapon: disablement field: 1D rule: chain on pressed: shoot