Travel upwards to safety, fending off waves of zombies while searching for ammos, cash and new weapons. There will be survivors to rescue, which some will fight with you, others provide cash rewards, or help to search for more items.

As you repeat your moves, you can upgrade your skills, or even release more monsters variety as you satisfy certain conditions. Release enough monsters, and a boss will be release into the game. You can only advance after defeating the boss, or be trap in an endless loop.

Player must defeat all 3 bosses to complete the game.