Great game and incredibly polished. The idea of tying the countdown to the shooting is fairly creative especially when it speeds up later on. Trading health for upgrades might filter out some players I feel, albeit I didn't have an issue with it as most upgrades leading to more damage inevitably lead to faster timer regain from killing enemies faster so it flows very well. I feel the RNG of spawning enemies could be causing some problems (especially with the pufferfishes bodyblocking each others hearts) and maybe some fine tuning there could be warranted but I still beat the game fairly comfortably, another feedback is perhaps scrapping the projectile speed upgrade as there isn't really enemies that require tracking but a projectile size upgrade would be a great replacement to accomplish something similar but benefits you in a game where most enemies walk straight towards you. I *did not* have an especially challenging time and *did not* try all to many runs, so fair to say I loved the game!