While an interesting concept, I feel like the demo for Parallel Dungeons failed to really showcase the core mechanic (of fighting in multiple parallel universes) in a compelling way.

With the meager few items you can obtain in the shop for the tutorial dungeon we see, it's not really possible to form much of a coherent strategy to build our deck around.

In my opinion, strategy games (but especially deckbuilders) need to be able to foster the scientific method. You need to make a hypothesis, and then test it to see if your guess works. And this doesn't really let you test out much in the way of strategy or synergy beyond the simplest of choices (do you want a constant bonus, or a variable one?)

That's not to say I think the full game will necessarily be lacking. But the demo, imo, is not doing much to paint the game as a whole in a compelling light.