The fundamentals of the game are simple: you fight waves of enemies until you die. Every 3 waves, you must vanquish a Boss before moving on. As you kill Monsters and gather Unholy Tomes, you obtain experience points needed to raise your level. At each new level, you are rewarded with varying amounts of Promotion Points, which in turn can be used to raise your five character stats, enhance your weapons or to obtain armour. But be warned: as you gain levels, so do your enemies. Z1:CG includes five different weapons, each graded from level 1 to level 10. When a weapon reaches level 5, it becomes a more powerful version of its basic form. There are many Items in Z1:CG to help you survive just a little bit longer.

In Zombietron, you will face endless hordes of monsters. Different types of Zombies, of course; but also Vampires, Ghouls, Werewolves, Killer Clowns and many other casual monsters. The real fun, however, starts with the bosses. Not only are they exceedingly tougher than other enemies, but they can also have special abilities such as spawning monsters or vomiting acid all over your frail body.