The older C&C games (C&C1, Red Alert 1, Tiberian Sun) are free to download and would easily run. The newer ones Red Alert 2 and Generals would work too (although Generals would probably need to have its graphics turned down.
Let me do some research and see what I can find but tbh retro games and indie games will probably be your main port of calls.
Let me do some research and see what I can find but tbh retro games and indie games will probably be your main port of calls.