Use the "Event" button on the following stages to get the corresponding effect:
STAGE - EFFECT 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.
ACHIEVEMENT - HOW TO UNLOCK Brain Surgery - 100 Brains sucked. d6 Admires You - All Gold medals. d6 Commends You - All Bronze medals. d6 Respects You - All Silver medals. Dynami-Te-He - 1000 Zombies blown up. Extinction - 100,000 Zombies killed. Friend of Bruce - All levels unlocked. Friend of d6 - All Developer medals. Graduation - Complete zombie academy. Hot To Trot - Last 30 seconds with 50+ zombies on fire. Murder On The Dance Floor - 1000 Zombies sent 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.