Earn a bronze or better medal in a single player level to unlock it in multi-player mode.
Silver medal bonuses:
Unlock the following bonuses by earning the corresponding numbers of silver medals:
BONUS - SILVER MEDALS
Zombie Vision - 1 silver medal.
Art - 4 silver medals.
Sketch Vision - 12 silver medals.
Sepia Vision - All silver medals.
Use the "Event" button on the following stages to get the corresponding results:
STAGE - RESULT
Woods - Rain slows down zombies; torch is extinguished and cannot set zombies on fire, but can still scare them; zombies that are already on fire remain burning.
Cemetery - Divine ray kills zombies.
Suburbia - UFO abducts zombies.
Drive-In - Plays music that makes zombies dance briefly.
Military Base - Line of TNT drops down.
Secret Lab - Three lasers rotates around the middle of the level that will kill everything.
Brain Surgery - Suck 100 Brains
d6 Admires You - Get All Gold medals.
d6 Commends You - Get All Bronze medals.
d6 Respects You - Get All Silver medals.
Dynami-Te-He - Blow up 1000 Zombies.
Extinction - Kill 100,000 Zombies.
Graduation - Complete Zombie Academy.
Hot To Trot - Last 30 seconds with 50+ zombies on fire.
Murder On The Dance Floor - Send 1000 Zombies Dancing
Paint The Town Red - Fill the screen with the maximum amount of blood on any level.
Red Shirt - Kill the away team Zombie.
Texas Style - 100 Chainsaw Combos.
Tourist - All Arcade levels unlocked.
Friend of Bruce - All levels unlocked.
Friend of d6 - All Developer medals.
"In Space" trophies:
No Time To Bleed - Get 100 Gatling Gun combos on the Engine Room.
Transporter Accident - Transport 1000 Zombies off the Mothership Bridge.
Top Ten - Beat ten of your friends in any leaderboard on either the Engine Room or Mothership Bridge.
Extreme Survivor - Survive 5 minutes with one life in Survival mode on Extreme difficulty on either Engine Room or Mothership Bridge.
"Zombie Sushi" trophies:
This Is My Boomstick - 100 Shotgun combos on either the Shrine or Castle.
1.21 Jigawatts - Electrify 1000 Zombies on the Shrine.
Top Ten - Beat ten of your friends in any leaderboard on either the Shrine or Castle.
Extreme Survivor - Survive for 5 minutes with one life in Survival mode on Extreme difficulty on either the Shrine or Castle.