Note: This procedure involves editing a game file; create a backup copy of the file before proceeding. Use a text editor to edit the "rebels.cfg" file in the game folder. Find the entry "checkvideo=#" (must be the very last). Set the value equal to 6, so that the line now reads "checkvideo=6". Save the changes, close the file and run the game. You can now start on any level.
Rebels: Prison Escape