I was playing and accidently hit the "~" key and a sort of cheat grey screen came on the bottom of the map, but you can't really do anything with it. You can hit the key and turn the grey screen on and off, but you can't type anything or interact or enter anything.

Was this suppose to be a cheat menu at some point? or is it something else i don't know about.

It's probably the console, which a lot of games at that time had. There are most likely console commands you can enter, if you can figure out a way to enter them into it.