This game more or less just "showed up" one day out of nowhere. "Oh, it's like Hearthstone, but singleplayer", I thought. I play it for a while, and wow. Just wow.
It essentially created today's deckbuilding roguelikes, and it hit it out of the park on its first try. Despite the many clones, no one has managed to to surpass the greatness that is Slay the Spire. The amount of different combos, strategies, the variation in gameplay and the level of control you have in the RNG has not been bested by anybody else yet.
I cannot wait to see what Mega Crit Games do next.