So my latest time-waster is a game called Ravenfield. It's here: http://store.steampowered.com/app/636480/Ravenfield/

I don't know what it is about it, but it's simple yet very engaging. It's single player, but there are lots of options, vehicles, weapons, etc. I haven't played a lot of FPS games, but this one has me hooked. The ragdoll physics are a pretty nice touch. Lately I've been "sniping" with the revolver for no good reason at all.

If you're looking for a cheap, simple, single player game for when you have a couple minutes to kill, give it a look. It'd also be good for kids, too. There's no blood or gore, just the red or blue blobs from the bots. No body parts flying off or anything either. And single player means no "online interaction" with other gamers.

My aging PC plays it really well on the default settings.