Every tile has an associated byte value, indicating the action to execute if Rex, an enemy or a shot collides with it.

Value	Action
0x00	Decorative tile. Anyone can pass trough it. The tile is drawn over Rex or the enemy
0x01	Platform tile. Anyone can walk over it and pass trought it if jumped from below
0x02	Wall tile (solid). Nobody can move trough this tile
0x03	Not used in game
0x04	Destructible tile. Needs 3 hits to destroy
0x05	Destructible tile. Needs 2 hits to destroy
0x06	Destructible tile. Needs 1 hit to destroy
0x07	Respawn activated
0x08	Shield recharging
0x09	Not used in game
0x0A	Get Laser weapon
0x0B	Get Multiple weapon
0x0C	Get Spray weapon
0x0D	Get Double Fire weapon
0x0E	Enemy always crouch and hopefully(?) fire
0x0F	Enemy always jump
0x10	Enemy can crouch and fire
0x11	Enemy can jump
0x12	Elevator