I guess you are right, though I do have a description where I describe the basic premise, it is not complete.
So, in the game there are 3 main menus, but I had time to make only the central one that allows you to place tiles. The purpose of the game is to create and expand/manage the dungeon so that you survive for as many days as possible. In the tile menu you can place 3 different kinds of passages, the core(a blue tile with an entrance) and the stairs from which the enemies will come. To be considered complete the dungeon has to have a path from the stairs to the crystal. In addition to those tiles you have the treasure chest(yellow) and the monster spawner tiles(green) that you can place on top of passages tiles. To place tiles use left click and to rotate the tiles use Q and R
Each tile consumes a certain amount of soul(the currency in the top right corner) on the beggining of every wave(day) in addition to that the enemies that have stayed alive through the wave also consume soul every day they stay alive. To replenish soul the heroes that invade the dungeon have to kill enemies, walk in the dungeon or die. But all of these actions will increase the strength of the next wave of heroes. To reduce the strength of the next wave, you need to have the hero pick up the treasure chest and then retreat with it.
(Also there is a bug that you can click the start day button even when the heroes are attacking causing the game loop to freak out and potentially break so please wait until there are no more enemies on screen before pressing it again)