Played the game and noticed a major performance issue. When I unlocked the lightning chain upgrade, it severely lags the entire game causing frame rate drop. Sometimes it stutters. This does not happen however if I unlock it on early waves but becomes a problem on later waves when there are many enemies.
The gameplay loop is quite fun honestly although the purple orb projectile that was shot by the enemies felt confusing to me. Maybe set it to red color instead to match the color of the enemy. Another thing is the stats on the bottom of the screen. Honestly, I think it should relocate to the right side as right now is pretty much empty. With that, the text size also can be adjusted to further improve visibility of the stats. Also I do wish the game allows me to see the short description of the upgrades that I purchased during something like pause menu as I do want to keep track not just the list but also descriptions as well.
Overall, it's a simple but fun gameplay loop as this also brings back childhood memories with some roguelike upgrade twist. Looking forward to the future updates! :D