Overtake is a bit weird with how it handles the disks. You need to:
- Boot with the system disk on drive 1 and data disk A on drive 2 - Select "game" from the first menu - Wait a long time until it requests disk B - At this point the machine should have ejected the system disk from drive 1 (the X68k has a Mac-like software-controlled ejection mechanism). Insert data disk B in its place. - It will continue loading and eventually show another menu where you can actually start the game
It seems to have a lot of graphical glitches, though.