Crushed monsters block player movement

In early versions of Doom, the player would not be able to step over corpses if they were killed by a crushing ceiling.

Monsters that were killed first and then crushed would properly allow players to walk "through" the corpse. However, if the monster was killed by the crushing ceiling and immediately became a pool of blood and flesh, players and monsters would not be able to cross over the pool of blood, and would instead have to walk around it.