The player views the action from a first-person perspective and must survive demon-filled levels, find keys, operate switches, and reach each exit. Weapons and ammunition are collected during exploration, while health and armor provide limited protection.

The campaign progresses through 30 regular levels, two secret levels, and a final encounter. Enemies differ in movement, attacks, and durability, so positioning and weapon choice matter. The DOS release also supports single-player, cooperative, and competitive multiplayer modes through its original networking and modem or serial options.

Explore every room carefully because secret areas often contain weapons, ammunition, armor, or power-ups. Conserve scarce ammunition for stronger enemies, and use the Super Shotgun at close range when its wide spread is effective.

Keep moving, use doors and corners to separate enemies, and learn the locations of damaging floors and ambushes. Save before risky encounters, especially when entering unfamiliar rooms or approaching a boss fight.

• Use the automap to identify unexplored corridors and missed branches.
• Avoid wasting powerful weapons on weak enemies when safer alternatives are available.
• In multiplayer, control narrow routes and deny access to important items.