What’s the best way to make a simple game feel fun and not boring?

First, make sure the controls feel smooth and responsive, because bad control can ruin even a great idea. Then add small rewards like sounds, flashes, or points so the player feels progress all the time. Good pacing is also important: the game should not feel too slow or too stressful. I also learned a lot from reading the official Kongregate docs here: https://docs.kongregate.com/
because they explain how players interact with games on the platform. When you understand the players, making a fun game becomes much easier.