The Bloodbath Arena Multiplayer Mode Add-on for Dead Island (Xbox 360) has 10 achievements worth 250 gamerscore.
Survive a wave of enemies in any Arena.
Set 5 enemies on fire and then kill them with explosives.
Survive 5 waves using only your fists and legs.
Kill enemies of 6 different types during a single round.
Survive 5 waves in each of the 4 Arenas.
Survive 15 consecutive waves using the analog combat controls.
Survive 15 consecutive waves with each of the 4 characters.
Survive 10 consecutive waves using only custom weapons.
Survive 30 consecutive waves with at least one co-op player.
Survive wave 30.