Official Quakewiki Video - Quake - E1M4 - the Grisly Grotto (Deathmatch)

Replacing Keys with a Rocket Launcher is possibly the best trick to these levels. Think about it, the key is in a hard to reach location that would serve as a perfect place for the best gun in the game (the first Episode doesn't have a Thunderbolt, even in Deathmatch).