I've seem there before back in the day. Click on Cancel in that pop up enough times for it to go away, then you can type. Type ASSIGN ENV: RAM:
That will tell that ENV to go somewhere (to the RAM) and it will not bother you anymore.
Type game-crunched.exe again and it may work!
If not, try to type game.exe instead.
Sorry for the long procedure but that's how prototypes are, and thanks for downloading it anyway!