Also, Universe Sandbox is a great program for those who are interested in physics, gravity, space, and the ability to completely customize our solar system (and whole galaxies) to see what would happen. Like, what if earth was the size of our sun? The program automatically shows what would happen with actual scientific method/physics, plus a lot more.
It's only 2 dollars on steam right now, it's very much worth it for anyone interested in that kind of thing, it's not a "game", more of a program, but you can control pretty much anything and adjust anything from size to speed to testing light speed and all kinds of stuff.
“Anna, my strong, terrifying Anna.” -Cas
"You lack the requisite spine and testicular fortitude to study under me" -Elodin