I used to love RTS games as a kid. I kind of fell off of them when they started to really emphasize the e-sports angle. Mostly because I wasn't really good enough to enjoy them and there seemed to be an ever increasing focus on "more APM". However, I recently picked up "Starship Troopers: Terran Command" and loved it. It was built to just be a campaign focused single player RTS. It's such a fun game, and doesn't overstay its welcome.