Non-Pixel Explosions is a modification for Quake that gets rid of the pixels around the main explosion of Rocket Launchers, Grenade Launchers, Ogres, and Spawns. Note that this modification, most likely due to oversight, does not change the effect on Radioactive Containers.
This modification was made in response to the large number of complaints about the "unrealistic" pixelated explosions. According to the author, the explosions belonged more in a game like Paratrooper for the Apple II.
Note this fix will however get rid of the dynamic lighting on the explosion effect, meaning the light from a Rocket Launcher projectile will appear to immediately shut off when it collides with a wall.