It’s been a long time coming, but The Legend of Bum-Bo is coming out on Steam this week: Tuesday, to be exact. As of right now, you can pre-order the game, which is Edmund McMillen’s follow-up prequel to his hit The Binding of Isaac, for a 15% discount. Even after all the dribs and drabs we’ve seen of The Legend of Bum-Bo over the past couple years, I have to admit I’m still not exactly sure what it is. I have the box copy down fine: It’s turn-based, includes some match-three elements, and looks like a papercraft version of McMillen’s distinctive art from Isaac. But how does it actually work? That’s been a big mystery to me – at least until now. Bum-bo has a lot of that randomized goodness that made The Binding of Isaac so compelling. The Steam page says Bum-Bo has more than 100 unique items, each of which can be upgraded and modified, plus more than 80 ‘trinkets’ that confer passive bonuses. There are also four playable characters, 10 bosses, and 30 different enemies to encounter.