Go, go non-traditional viewport sizes! Really enjoyed the visual style and feel of the game. Super clean. One new enemy type would have gone a long way towards keeping the levels interesting! Missing out on the first gamble each round felt really bad, and made me not want to risk it at all. Perhaps having a high chance of getting a weak power-up, and then being able to gamble to strengthen it, with an increasing chance of you getting nothing at all?
Really great job!