Oh KSP is awesome alright! I haven't played it in a while. In my last game I tried to go through a career mode playthrough, before that I played all sandbox mode. But then the game crashed on me after I sent up my first real science orbiting station. So I haven't played since. That was a couple months ago, so they've probably fixed whatever problem I came across, but it kinda did turn me off from the game. I was just so engrossed in my mission and then *poof* it's gone. It was like watching your spaceship explode with no autosave.
Mind you that was the only time ever the game has crashed for me. It has always seemed so stable. So to anyone reading, do not let that dissuade you from trying this game. If you're into "space stuff", you will like KSP
Cities: Skylines is a great city building game, I would try that one. Banished is also very fun, I've gotten a lot of gaming time out of it. I would try the vanilla game first to get familiar with everything, and then try the Colonial Charter mod, which adds a lot of new content to the game. Playing the "Adam and Eve" starting mechanic is a lot of fun, but mind you I haven't tried any of the other ones that the mod sets you up with. As for mods for Cities: Skylines, there are so many of them, that I don't really know which to recommend. There used to be "must use" mods (for me), but the devs integrated some of them into the game. Some stopped working, some were abandoned by devs, etc. The mod that turns off chirpy is probably a must, but other than that I have no idea. That's one issue with the game - if you step away from it for a couple months, you have to sit down and figure out which mods are now "must have". Maybe it's just me but that would change all the time.
Planetbase was a very fun game that you might be into. You land a bunch of resources and dudes on a planet and have to build a base. It's a very addicting base building game, even though after a while you realize there could have been a lot more to it. I think I bought it for $5 - well worth it at that price. No idea what it's going for now but I've definitely had a lot of fun with it.