Go into the Hacking Engine on the game and go into CHEAT.EXE.  This is where you can enter the following codes:

Unlimited Ammo

Type in 1DDF2556 as a code.

Unlimited Focus

Type in 69E5D9E4 as a code.

God Mode

Type in 7F4DF451 as a code.

Maximum Firepower

Type in 0034AFFF as a code.

Invisibility

Type in FFFFFFF1 as a code.

Multiplayer Fighting

Type in D5C55D1E as a code.

Sparks' Construct in Training Mode

Type in 13D2C77F as a code.