A cool concept! I think it's very tough and it's really difficult to understand the UI like where health is and what specifically the barrier is doing. I'd also say that enemy projectiles are really tough to see being the colour that they are. If they were more vibrant I think it would make it better. It would also be good to show the player their final score at the end instead of reloading the level instantly, otherwise I don't know what score I got! It's a pretty tough game but it has the simple yet fun feeling that if expanded upon with better art, animation and particle effects, it could make it great! Good job for 48 hours work.