It's a "side-scrolling" real-time strategy game, pixelart style, with a few small "rouge-lite" elements. You have to collect and farm creatures, various bizarre creatures, to further develop your territory and eventually defeat the evil force that has been organizing against you throughout the game.

Depending on the playthrough, various creatures can be acquired and farmed, many of which have unique characteristics.
By purchasing these creatures you can gain resources (energy).

You can use the energy to upgrade walls, lasers, mines and a wide range of other defensive equipment. The game has a passive development system, your repertoire of tools will evolve in whatever direction the system deems useful to you.

And what are these defences against?
Against mould, which, like an infection, overwhelms and destroys the living things the player builds. In other words, there is no arch-villain, some being above all. You simply have to repel and eventually defeat the attacks of the mould that constantly besieges the night.