Well, I somehow have 40 hours in the game, so there’s that. Probably more than 10 hours of this is my wife; she had beaten Act 3 boss too. Watches me play, gives some advice so I probably don’t do as much stupid mistakes as I’d do alone.
It’s a great feeling: so many hours of constant learning and mastering. Most strategy games would have included a lot of bore in there. Say, @BloodyBattleBrain likes Age of Wonders 3, I think, and I’d agree this is one of the best empire building games ever made, but it still has boring campaigns, map mopping up, 7 armies siege battles that you want to quick resolve. And even something like Hearthstone which is somewhat similar in its design will have a hundred fights of forced grind while you buy packs hoping to get that card that you need for a deck people on the Internet recommend. And Slay the Spire doesn’t have all this, is bullshitless.
The only other game like that I remember is Desktop Dungeons. It too had a lot of gameplay till you “officially” win it and then there was an endless myriad of increasingly hard challenges I never got to do. StS has ascension mode and Daily Challenge. I’ll probably never touch them and will still have more gameplay than most big games provide before they feel “solved”.