Forum Overview :: Sigil :: An example of Doom exploiting its two-dimensionality:

[quote name="Dream Cast"]Monsters in Doom are infinitely tall, and block 100% of projectiles as long as they're alive. This makes them ridiculously effective as mobile shields. On top of that, monsters of different types will do friendly fire damage to one another, which usually triggers infighting between them. Half the battle in some large-scale engagements is figuring out which monsters to stack in front of which. You'll eventually find yourself running around in circles herding melee demons at 60 MPH, while a gigantic boss monster spews rockets into the morass, sending gibs flying everywhere. It's goofy as hell and dumb as shit and metal as fuck.[/quote]