Scavenge Mode is a competitive mode, and it involves two teams of 4. The first team plays a round as Survivors collecting gas cans to fill up a generator. They fill up with as many possible, up to 16. The cans are scattered all over the map, sometimes single, sometimes in pairs. Spitter goo can ignite cans lying on the ground, and there's always the stray shot... so be careful. Each can poured into the generator gives +20 seconds to the clock. When time runs out, the round is over. The only exception is if a Survivor is carrying a gas can. In that case, the round continues as such until: A) it's dropped, or B) the can is poured into the generator, adding more time.

The Infected team of 4 basically plays the same as Versus, with everyone respawning as the various Special Infected. Your main goal is to prevent the other team from getting gas cans. However many gas cans the first team gets in, the second team must match or surpass that to tie or win the round. Scavenge mode plays Best of 5, and is a fun mode for those who enjoy Versus but don't have an hour+ to blow.

Realism Mode is like Campaign, but made more difficult with certain tweaks. It can be played on any difficulty, but changes include:

- Zombies take more damage before dying, so headshots are important
- No Survivor HUD outlines, so maintaining line of sight is vital
- Witches kill you in a single scratch now... Not incapped, killed
- There are NO Survivor Closets, so the only way to come back from death is via Defib

I've only played half of Dead Center on Realism, and it was intense. You don't realize how much help the Survivor HUD outlines are until you're without them. It really does make it feel more realistic, if that could ever be said about a zombie apocalypse.