[pif]

Edit: thanks to commenters for the reference to KSP. I had to ask Wikipedia what it is, and the first sentence is: "Kerbal Space Program (KSP) is a space flight simulation video game developed by Mexican studio Squad".

Mexicans forgetting about Latin is even worse than native English speaker doing the same!

[OkayPhysicist]

It wasn't a mistake. KSP takes place in a solar system that is similar, but not identical to our own, and the planet the the space center is on, Kerbin, has a moon, called Mun.

[deepsun]

They didn't forget anything. Try playing it for 10 minutes, it's fun :)