The following are known Action Replay Codes for Half-Life on Sony Playstation 2 (PS2). These codes were also known as GameShark Codes and in most cases will work on both devices.

Device Compatibility: Action Replay & GameShark (Version 1 & 2)

Master Code – Must Be On
EC8783A8 1431D934

Xen Gravity Cheat
4CA57342 1456F025

Invincibility Cheat
4CA5735A 1456F025

Inf Ammo Cheat
4CA57372 1456F025

Invisibility Cheat
4CA5738A 1456F025

Slow Motion Cheat
4CA573A2 1456F025

Alien Mode Cheat
4CA573BA 1456F025