[SkyBelow]

Advance Wars has a map creator and the AI can play on it. In theory one could get an AI to generate maps given the rules of the map creator and then users can implement them. Per my memory, no way to share, so it'll be a bit harder to setup and you can't do things like give the enemy units whose location you don't know, but it achieves a near infinite replay value. With some more work and one could have a new AI interface with an emulator and play the game instead of using the built in AI, if one finds it is no longer challenging. Thought that is probably reaching the scale where remaking the game from scratch would give one more freedom and control (and ability to monetize).