The ghouls, which previously appeared in the "Ghouls' Forest" Doom levels before making it to the multiplayer game, are mostly huge floating scary heads which kill people (Choke, Sjas, Creeper, Jitterskull, Frostbite). The humans are specialists armed with weapons of various kinds, depending on their class (Marine, Hunter, Cyborg, Ghostbuster, Engineer). Basically, one team is the Nightmare Fuel and the other team are the unfortunate recipients.
Ghouls vs. Humans: Legacy of Darkness is a fan-made, expanded version which adds a lot of new classes for both teams, and you're more likely to find it played online these days.
Ghouls vs. Humans provides examples of:
- All There in the Manual: The author's blog used to contain backstories for all the ghouls and characters. Then the author deleted them all, deciding they were "no longer needed". Thankfully, they can still be found at the Internet Archive (see the "Characters" section in the menu).
- An Ice Person: Frostbite, which looks like it's made of ice and has cold-based attacks.
- Archer Archetype: The Hunter class. He's sort of Born in the Wrong Century, as he prefers to use medieval weaponry and armor despite living in what looks like modern times.
- Badass Santa: Used to be one of the classes.
- Cyborg: One of the human classes.
- Deadly Disc: One of the Engineer's weapons.
- Fire, Ice, Lightning: The Hunger has fire, ice and lightning arrows.
- Flash Step: The Jitterskull always moves like this, which makes it really hard to control.
- Jet Pack: Used by the Cyborg.
- Joke Character: The Christmas Update introduced Santa to the humans team, with "Holly berry traps" and a "star cannon". A few months later he was reskinned into the Engineer.
- Jump Scare: All ghouls rely on this to some extent, but this is the Creeper's main shtick.
- Lightning Bruiser: Pretty much all the ghouls.
- Make Me Wanna Shout: Sjas's supersonic shout attack.
- Mouth Cam: Most of the ghouls, when you play as them.
- Names to Run Away from Really Fast: Choke, Frostbite, Jitterskull.
- Our Ghouls Are Creepier: They're giant floating heads, for one. They're still undead though.
- Red Eyes, Take Warning: The Jitterskull, "because we all know that red eyes are EVILLLL.".
- Technicolor Death: The Sjasface, Jitterskull and Creeper die in a fiery explosion.
- Versus Title