Can I move move games to the D: drive??? Such as OMSI...ect???

a lot of games put registry files and other things that relate to the folder it was installed, so if it was on C, moving it to D won't work.

There are a few options

1. Uninstall the game and install it on D
2. If it's a steam game, there is a program called steammover or something like that that will let you move steam games and it does it all and fixes all the registry stuff
3. There is also software called junction linker or something like that, that will basically watch whenever windows tries to call say c:\games\gameABC and redirect all calls to d:\games\gamesABC or wherever you move it.

Option 1 or 2 are probably the best. I've only used the juntion linker in cases of ramdisk games and such where changing the path wasn't an easy option.