The Peggle of Slay The Spire-likes.
Overdungeon is a real-time tower defense card game. You play cards to position defenses and units onto a board, which then fire or steadily march towards an enemy that's doing the same. There are no turns, though - cards operate on a cooldown, and the battle rages all the while.
What makes this glorious - and comparable to Peggle, in my eyes - is that it's more concerned with spectacle than strategy. It's a game unconcerned with runaway card multipliers, in which you can specialise in animals and steamroll opponents with swarms of chicks and alpacas. It's a game about swarms. The number of cannons in the header screenshot isn't a brief special ability, but a rapidly grown arsenal which fires continuously.
There's some replayability in trying different character classes and trying to maximise the quantity of certain unit types, but Overdungeon isn't a game you're going to lose hundreds of hours to like Slay The Spire. It's a game you're going to boot up every now and again (via Steam) when you want an easy endorphin hit, and it's going to deliver every time in the space of fifteen minutes.