Sure! Here's an example of a simple game that meets your requirements. In this game, you need to tap on enemies to kill them and earn points. As you earn more points, you can purchase upgrades such as damage boost, speed boost, flame effect, and more.
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In this game, enemies spawn randomly inside the game container. You can tap on them to kill them and earn 10 points. The score is displayed at the top. You can purchase various upgrades by accumulating points and then tapping on the upgrade buttons. The upgrades include damage boost, speed boost, and flame effect. Once the flame effect is activated, you can tap on enemies to kill them faster. You have a limited number of flames available.