Half-Life 2 adds in 'Buddha Mode' just for good measure, which allows you to take damage but almost never lets your HP fall below 1, effectively making you immortal. Latest builds add in a 'god2' and a corresponding 'buddha2' cheat code that both prevents the player from dying no matter what, not even from telefrags. Additionally, one infamous puzzle near the end of TNT: Evilution has the player navigating a maze of pillars take a wrong turn and you'll end up telefragging yourself. All bets are off on the last level of Doom 2, however.
In the Doom engine, God Mode (which is also the function of the Invulnerability Sphere, except that it tints your screen in silver as well as giving you the glowing God Mode eyes) only protects against 10,000 damage per shot.id Software almost always include a God Mode out of tradition.
