Simple and really fun! The controls are a bit hard to get used to at first but after a couple of deaths I got the hang of it and got pretty good (made it to wave 23 I think that's good? haha)
I liked the two kinds of attacks and it seemed well thought out for the enemy attack patterns. Would have liked to seen some sort of progression through the game though. Maybe the enemies can get tougher as the waves go along? I saw a couple of other games in this jam where they palette swapped the enemies and gave them different abilities/attack patterns. That might be an idea to explore as well.
Hope you keep working on the game and add more to it. The core mechanic is really fun and you could build a lot of interesting gameplay around it. :)