Yes, I
know I should be finishing Racundra for her Spring-launch, but dark nights have recently meant that KSP has absorbed much of my free time.
What is it? Well, you're in charge of a space programme on the planet Kerbin. There, little green Kerbals have decided to develop rocketry to explore their solar system. You get a stock of rocket parts, enthusiastic astronauts, a learning curve that is decidely vertical at first, and more laughs than you could imagine. This is definitely a game for Nerdy Kids Of The Space Age, which is me to a tee.
There's a "sandbox" mode where you can just develop and explore to your heart's content.
My first space station:

A minor accident on the Mun:

My first successful landing on Duna:

My disastrous attempt to place a small asteroid into orbit around Kerbin (I was attempting to aerobrake it, but came in too low):

And my new 1000-tonne orbital refuelling station. Somewhere to pop into for a Ginsters and monomethylhydrazine before my new missions to the gas giant Jool:

If you're curious to see what it's like, type KSP into youtube - there's a pile of videos there. There's a free trial version as a taster online, and the full version costs under £30.
Andy