I just bought the game and I can't even do anything in it. All I can do is run around, but the in-game crosshair stays in the center and my mouse cursor is there, and I cannot click anything, or use the arrow keys or anything in any menus, so I have to ctrl+alt+delete out of the game because I can't click quit because I can't do anything in the menus.

Hi Wotman.
Try to disable Steam overlay (or just start the rwr_game.exe directly without starting the game through Steam).
You might also have a third-party software that uses overlay running in the background? (like AMD Raptr, Desktop Fusion, etc). You might want to disable/close them.
If you don't have any of those running try to directly start RWR after a restart as first.
Do you have multiple monitors? If so try to disable all but one.
Hope this helps.