Thanks for the feedback. We're actually planning on continuing this into a full game later on. As for the upgrades it increased your damage and rate of fire by 1 unit per level. I'm planning on changing how that works though. Also we wanted to add some form of health regeneration system but didn't want to add the normal wait for it to come back system. If you keep an eye on my profile I'll be making a post when we fully release this. We'll make sure to keep your feedback in mind when making future versions of this too