Out of curiosity, are you familiar with other card games besides Slay the Spire? I find that while STS is a big influence, it's also drawing from other things. I fucking love Inscryption, and I have never played STS.
There are so many references to other card games, Magic: The Gathering in particular. I'm not certain, but I am pretty sure the 4 major NPCs are modeled off of player psychographics from that game. Also, while there's a focus on horror, and for good reason because Act 1 really sells the atmosphere, something I think that gets lost is that this game is fucking hilarious. It is such a delightful mix of horror and comedy and weirdness, just this wonderful love letter to card games of all sorts. For instance, like you I thought the "meat" of the ARG stuff was pretty trite. I do not care about the satanic game aspect, although the part about a game that completes and replicates itself though exploiting the player/designer I think is pretty interesting. But anyways, the thing that really sells the meta element is that the character it's being told through is such a spot on example of a real type of guy who plays card games. The mannerisms and way he talks about cards while interjecting over your gameplay is just spot on. It's incredible. I laughed a lot during the video sections.
I actually didn't care nearly as much for Act 1 as others did, I actually thought it dragged on a bit too long. The other parts were a lot easier to break mechanically and didn't overstay their welcome too much, though Act 3 is pretty long. But overall, the rote mechanics of the game aren't exactly what kept me coming back - it was more interesting to me just to see how those mechanics are used, and how they are are twisted versions of mechanics from other card games. Anyways, I feel weird talking about this game because my experience seems pretty out of step from the norm? Or maybe it's not. I feel like these things are underdiscussed, but also who even the fuck knows because all discussions of this game have to be hidden away.
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I definitely did not forget to put the 2020 GOTD Guru winner, azuarc in my sig!