We're glad you liked it! We originally had a different setting for the game in mind - a sci-fi-80s mix, but we ended up completely changing direction on the second day to the current poker theme due to not having a clue on how to properly execute the original theme, and we're happy we changed it seeing as it made the game unique.
I agree that the balancing would need some more work, but we were low on time, and I wrote the waves at 5AM on the 6th day. The game overall only had around two hours of proper playtesting. The last 10 waves were never played before submitting the game. As it stands now, the late tens and twenties plateau in difficulty, but afterwards it does start somewhat increasing difficulty. The fact I find most amusing is that you were 2 waves away from a new enemy :). New enemies are introduced every 4 - 8 waves or so. In total there are 50 waves with around half the enemies being introduced around the 23rd.
When you get the time, perhaps try finishing all 50 waves :).