blackjack with a twist, not bad but when game relies heavily on luck i prefer adding a permanent upgrade, its quite annoying when you have to lost everything once you lost. imagine your she has 20, and you has 18, but potential card are 2-6, will you accept your lose or Decide to Stand and a small chance that your tier 20 may gone?
anyway, art is good, i love it, could use some more juices, sound effect are nice, well if you want to develop this to a full game, in my opinion, it will need balance that it shouldn't relies heavily on Luck. Good Luck!