What Are the Best Strategy Games For Senior Citizens?

[Battlemind]

I have seen a lot of senior citizens (people older than 60 years) play different kinds of video games but I have not see any old people actually playing real time strategy games. One plausible reason I see is RTS games need a lot of thinking and planning and when you are older than 60 years, you will have a loss of cognitive functions so you might have difficulty in playing RTS games. By the way, what do you think are the best RTS games for senior citizens?