It's a clicker idle game thingie, with a dash of zombie thrown in!
Someone (definitely not you) has released a horrible virus that is turning people into mindless zombies! Luckily, being stupid-rich and ultra paranoid has really paid off because you happen to own The Last Bunker!
Open your doors to the tired (and slightly smelly) masses fleeing from the zombie hordes. Of courseā¦once survivors are rescued they will have to earn their keep, right? Process them through decontamination, the clinic, the cafe and the supply depot as fast as possible so they can get to work in your lab producing precious Science for you.
Use Science (and any collected Golden Brains that may drop from zombies or grateful survivors) to improve your bunker with all kinds of handy upgrades like extra turrets, zombie punji-pits, increased survivor spawn rates and more powerful clicks.
If you get tired of exploding zombies with your mouse, you can always use abilities to liberally scatter land mines and razor wire in front of your bunker. Or perhaps an airstrike will do the trick?