When you have a Mac that is surely capable of running TWoM, but it says on Mac Appstore that it doesn't support your hardware, it means there happened a system-related bug. It happens in many games and us and other devs reported this to Apple. Not sure when the fix may come.
If this happens, I highly recommend purchasing DRM-free version from Games Republic, and there is guarantee that there is no such system bug. The version is here:
https://gamesrepublic.com/game/strategy ... e,148.htmlCheers!