Wow, I had lots of fun with this! I played it through several times until I got to Cardthulu, but unfortunately he killed me. It seems like other people may not agree with me on this, but I feel like the enemy fighting parts have a bit of strategy to them (not clicking on the same card on the 2nd try, paying attention when the cards shuffle); it's mostly the "shop" level and the Cardthulu fight that feel too random. At least to me.
I can't believe that's your first game! It's incredible! And you didn't even use all 48 hours!? Awesome job!