I think I just played the saddest deckbuilder I’ve ever played, Iris and the Giant. The story is told in a very simple manner, but manages to make an emotional impact. It also plays a little differently than many card games, in that you also need to manage the geometry of new enemies entering the area where they can attack, and possibly be attacked. It may be beneficial to not kill one enemy to prevent another from getting into position.
One other difference is that cards are used up when played, and it’s game over if you run out of cards, so deciding when to take cards vs abilities during ‘level up’ becomes an important choice, along with whether you want to burn a card to get some loot along the way. I know this may turn some people off - it did me at first, but I didn’t find it too unpleasant.
It also has persistent unlocks between attempts to ‘win’ a campaign, and the ability to equip special abilities and allies between runs. While I didn’t enjoy it as much as Slay the Spire or Monster Train, recommend trying it. I’m pretty sure I got this in a Humble Choice or something, so many people may already have it. I didn’t expect too much going in but was pleasantly surprised. I didn’t enjoy the art style but liked the game enough to continue.