Ricocheting projectiles is a modification for Quake made by Kyle R. Hofmann. This modification allows Shotgun and Double-Barrelled Shotgun shots to ricochet off walls. This means that if a shot hits a corner, it will travel at an angle before producing a second shot.
While the Nailgun and Super Nailgun could potentially work, Hofmann found that he got constant overflow errors when using it, which made it unusable. The code therefore existed inside the source, but did not modify the mechanics in-game.