Kill 150 enemies using Analog Fighting controls.

Kill 250 zombies using blunt melee weapons.

Heal yourself with a medkit 100 times.

Play with 10 different co-op partners for at least 15 minutes each.

Kill 25 zombies with your bare fists.

Complete 5 quests with 3 co-op partners.

Join another player's game.

Kill 50 human enemies.

Kill 250 zombies with modified weapons.

Reach level 25.

Kill 250 zombies using edged melee weapons.

Sever 100 limbs.

Complete act I.