http://en.spaceengine.org/
To put it bluntly, Space Engine is not really a game, but more like a fun thing to check out whenever you're bored. Its like Universe Sandbox but here you don't just get to smash a bunch of balls together, you get to explore the balls...in depth (Did I mention it's fucking free? Universe Sandbox is $25? Seriously. 25 Smackeroonies to smash some colorful balls together with a minimal physics engine and this bitch is FREE to explore all of the infinity of fucking space!)
Basically it has fucking everything in space that we know about and whatever we don't know it generates it randomly and a lot of times the stuff it generates is cooler than exploring the moon or whatever planet is in our familiar Solar System. The controls are a bit finnicky but really all you need to know how to do is move with WASD (and Q & E for roll) and the mouse and you'll have a good time. You can literally click on any star you see, right click on it, go to it and explore it. Save whatever cool places you find and the game has a button for taking screenshots without the GUI which is handy because this game looks so damn good every screenshot can be a wallpaper.
I've also heard there are some mods, like you can add in a working USS Enterprise from Star Trek or whatever ship you want and fly it. Personally I just like zipping along at light speed in free roam.
I'll shut up and just show you some screenshots that I have personally taken from my travels. Including the coolest shit I've ever found in this game, and I challenge you all to try and top me ;)
I found some lovely landscapes filled with magenta and bluish colors
I found a "dead earth" Just by zooming about, I think this was even described as a "hot terra"
It had a great view but heres the weird thing, everything was cracked dried dirt and the riverbeds/canyons were dry as a bone. It didnt just LOOK like a dead earth...it WAS a dead earth... :shock: It even had this weird orange "smog" over most of the planet, getting this clear shot of the sky was pretty hard!
Hold onto your dick for the finale kids.
I also found a couple of bright stars near each other
And some "super planet" with 5 small moons that were also the size of a planet like earth
And a really mountainous looking mars with a cool little blood moon!
Alright kids, get ready to have your dicks flying off into Andromeda.
I came across a boring looking planet but it looked like it could have a great view unless the atmosphere fucked it up
Nope, it's fucking awesomeonly downside is you have to be in the icey part of the planet to see it, but then it got even BETTER

A view of not only fucking Andromeda (I think thats the galaxy?) but a god damn Aurora lightshow as well. Yeah, pretty much the most amazing thing you can ever find. The only way to make it better is if the landscape was a bit cooler.
Well shit I guess some lumpy snow mountains will do!
PRO TIPS
Basically, click any random star, right click and go to it, move mouse to the left and click the "planetary system" button this brings up another UI thing above that I think shows all the nearby...well, anything nearby, look through them and ignore stars or gas giants (theyre usually boring imo but check em out if you want!) a good keyword is "terra" or "desert". Click it, now move your camera around because once you click it in the UI, it selects it for you, now right click it and go to it and explore the planet! It can be kinda finnicky and you may accidentally click some invisible dot next to it so be careful on what you select, you can always just fly towards it manually with lightspeed. :P
One last thing to end this post (like it wasnt long enough already)
On the website there are some "HD" textures for the planets in our solar system, this includes a 11.5 GB download for earth with a fully accurate heightmap, surface map, HD cloud textures AND city light map. Now, I mentioned this isn't like Universe Sandbox, well it kinda is in some ways. You can move shit around, put the planets close together and whatnot. So imagine having a perfectly modelled recreation of your town, and fucking mars is looming over head. Or saturn. I'm not sure HOW to do it since I'm still learning the controls but I know you CAN
Alright enough reading, go download this shit and explore the stars! And use this thread to share your adventures!