To access the cheats menu, press the console key, or '
Once in, type 'cht_bEnableCheats = 3' without the quotes to turn on cheats. You can either use the menu, by pressing Escape and then F3, or type cheats in manually, to activate each individual cheat.
Note that you cannot gain achievements or set leaderboard scores for a session where you have been cheating. Also, you need to remember to turn the cheats off before your next play, using 'cht_bEnableCheats = 0'.
See below for a list of the cheats:
Auto aim cheat: cht_bAutoAim Display all the messages in NETRICSA: cht_bShowAllNetricsaMessages Enemies can't see you: cht_bInvisible Fly around and pass through walls: cht_bGhost Fly around: cht_bFly Gives specified amount of ammo for specified weapon: chtGiveAmmo() Gives specified amount of armor: ch_slGiveArmor Gives specified amount of health: cht_slGiveHealth Gives specified weapon: chtGiveWeapon() Gives all available weapons and max ammo: cht_bGiveAll God mode: cht_bGod Increased speed: cht_bTurbo Infinite Ammo: cht_bInfiniteAmmo Kill all enemies in line of sight except bosses: cht_bKillAll Kill the current boss: cht_bKillBoss Unlocks Mental Mode: cht_bUnlockMentalMode