The traditional mode of gameplay is Deathmatch; at the start of a round, players must choose a single pistol, a unique weapon, and a special item.

Unlike the buy menu in Counter-Strike, these weapons are free and have limited ammunition, which makes tactical usage crucial.

The game also includes a "last man standing" mode, which plays like a deathmatch, but without respawning after death.

Some unique features in this mode include a move called "Adrenaline Rush", similar to Bullet Time.

Action Half-Life was the favored modification for a small subculture described by Rock, Paper, Shotgun's writer Quintin Smith as a "mad cabal of mappers who obsessed over easter eggs",[1] with some levels containing secret areas much larger and more complex than the main level.