I can't even remember...one of those internet paths you take down a rabbit hole.
I found it in 2011. Before that I was stuck in John Tillers East Front, which left a lot to be desired as far as AI and interface. I literally get motion sickness when playing most FPS, the quick screen motions make me dizzy, long after playing; so that never did much for me.
CM has everything I want; challenging, fun, multiple game formats. Just started pbem and it is adding yet another dimension.