Half-Life Cheats...
Alien Mode
At the cheat screen enter: Up, Triangle, Up, Triangle, Up, Triangle, Up, Triangle.
Infinite Ammo
At the cheat screen enter: Down, X, Left, Circle, Down, X, Left, Circle.
Invincibility
At the cheat screen enter: Left, Square, Up, Triangle, Right, Circle, Down, X.
Invisibility
At the cheat screen enter: Left, Square, Right, Circle, Left, Square, Right, Circle.
Low Gravity
At the cheat screen enter: Up, Triangle, Down, X, Up, Triangle, Down, X.
Pro Action Replay Cheats
(M)
0E3C7DF2 1645EBB3
0C1AB027 F8A9CB9F
Unlock Xen Grav Cheat
2C291BED F8FC3F7E
Unlock Invincibility Cheat
2C291B05 F8FC3F7E
Unlock Inf Ammo Cheat
2C291B1D F8FC3F7E
Unlock Invisibility Cheat
2C291B35 F8FC3F7E
Unlock Slow Motion Cheat
2C291B4D F8FC3F7E
Unlock Alien Mode Cheat
2C291B65 F8FC3F7E
Slow Motion
At the cheat screen enter: Right, Square, Up, Triangle, Right, Square, Up, Triangle.