What to play when you're done with Kerbal!

I heard you guys like Kerbal Space Program, so I figured I'd tip you on something similar, but different.
Orbiter Space Flight Simulator is a game that in some ways is pretty similar to Kerbal, and in some ways pretty different.

First of all, it takes place in our solar system! (but you can add fictional solar systems through mods)

It includes all eight planets, as well as some smaller bodies.

The flying is what makes Orbiter great! Where Kerbal focuses on engineering, leaving simple controls for flight, Orbiter is a straight up flight simulator!

The rockets handle realistically, and you're in full control.

With the guidance of computer planning, you do everything manually, and the flight computer makes sure you have precise info.
Aligning planes, planning escape burns, stabilizing your orbits, there's on-board systems to help you with all of it.

Wanna dock with the ISS?

Or maybe visit the moon?

Land on mars?

Fly by Jupiter!

Orbiter comes with a handful of spaceships, but there's tons more to download, fictional and real, for various purposes.
There is mod support for building rockets, but it's not really designed for it - so that's one aspect missing compared to KSP

And guess what? It's free! Orbiter is developed by Dr. Martin Schweiger at UCL, and you can grab it http://orbit.medphys.ucl.ac.uk/
(I recommend the beta - it has really high texture versions of Earth, Mars and the Moon available, redesigned ships, and graphical tweaks, including terrain)