An incredibly soothing piece of Software that lets you chill out and explore the Universe.
I'll emphasize that this isn't necessarily a game since there are no objectives or NPCs. This game is for those who just like to walk around the entire Universe and admire the view.

I played the free development version of this for a good while before this and favored the in-game ship simulation mechanics (that you can access through the menus on the left side). The system lets you pick out a ship (small to bloody huge (600m+)) and then gives you various control schemes for different situations you can fly in (horizon marker for planetary/atmospheric flight; orbital controls; docking controls; warp controls).

Picking up where I left off in the older versions, I spawned a starship in Orbit of Earth before hitting the gas in direction of the other side of the galaxy - only allowing myself to plot my route there based on the stars I can pick out from the constantly-refreshing constellations around me. All this while listening to an Audiobook of Carl Sagan's "Pale Blue Dot" (You can find it here if you're interested in the playlist.

There's nothing better than marking your destination and hitting the warp button. The autopilot does the hard work and you get to sit back and watch the warp bubble form around your vessel. As you travel faster than light, I can't get over how awesome it is to see the light from passing stars getting warped through your ships' warp field.