Interesting concept! My first suggestion would be to make purchasing abilities done with hotkeys instead of using a menu. Needing to open the menu every few seconds to buy a jump felt like the game was getting in my way. It might even be better to forgo the store entirely, and just let the player jump, sprint etc. but deduct the time cost when they do it. That would make the experience smoother and ultimately more fun. Good luck, and I hope you continue to develop this!