It's cute.
Your instructions aren't very good - it took me a while to figure out which character I was controlling and how to open the cards. The vending machine on the right was cut off - but there was one in the middle that did the same.
After a few minutes I was bored because I had nothing to do in the game but wait for people to buy the cards. I don't know if I'm missing something or whether one should just continue to buy and open cards until your money is up.
I found it strange that your game was only using the bottom third of the screen and not the entire screen.
I think it has potential if you develop the "bigger idea".