Yet Another Zombie Survivors Maps & Modes
Two maps are live at 1.0 with at least three more on the way. Each map has unique enemies, hazards, and unlockable modes - endless, hardcore, boss rush and one-hit.

Isolated City
The first map. Spitter is the map-unique enemy. Survive 15 minutes here to unlock Huntress; endless, hardcore, boss rush and one-hit modes unlock as you clear it.
Vile Wasteland
The second map, a desert ruin. Unique enemies: Mummy, Scarab, Desert Spitter, Big Mummy. Worm hazard eats zombies (500 total feeds the Om Nom Nom achievement). Find Sanji the Rabbit for the Curly Little Potato achievement.
Unknown Areas
At least three more maps are confirmed as the game develops. The selection screen hints at more content coming after 1.0.
Current Maps & Mode Sequence
Isolated City → (survive 20 min unlocks Vile Wasteland) → Vile Wasteland. Each map unlocks endless mode, then hardcore, boss rush and one-hit as you clear achievements. Unlock Huntress by surviving 15 minutes in Isolated City, and find Sanji the Rabbit on Vile Wasteland for a hidden achievement.