The playable demo is the last dual format disk created for The One by Rob Northern before it went over to 100% Amiga. I had no luck at all with the first disk I had but the second I purchased I finally got working with 1.3 version 34.20 no glitches. This is a strange solution but it only worked with a GVP sidecar plugged in with 4MB memory. I had tried a 1200, 600 and the 500 stock with no luck.
I was unable to copy the disk.
https://www.scuzzscink.com/amiga/scu...ary22_2701.htm
Eventually I purchased the boxed version of the game.