You pick a hero, go into a dungeon and use guns or melee weapons to get deeper and deeper into the dungeon, much like other roguelikes. You die but you can keep your currency and whatnot, which leads to the grind that fans of the genre are used to. As a F2P mobile game it's decent. The ads aren't that bothersome, and even though touch screens are shit, they keep it simple by only allowing you to move and shoot, which makes hitting the right button easy, while also not taking up half the screen.