Once you get bored of the base game, Slay the Spire also has an extremely robust and high quality modding community. I got around 200 hours out of the base game and then an additional 250 on top of that out of modded classes and setting overhauls.
StS: Downfall in particular is extremely high quality and was in fact so popular that it got its own Steam store page, like a free DLC would. Highly recommend.