But if you want a bug report, there's nothing much I can say. Duke loads, it doesn't play a demo, shows the menu screen after a push of the spacebar then promptly freezes when you try to start a game. I have a Pegasos with Radeon too. I can confirm that it doesn't work for at least one other Pegasos/Radeon user too.
Same here - Pegasos G3-600, 384MB RAM, Radeon 7000. It gets as far as printing "Code Size:64832 bytes (1795 labels)" in the console window then hangs the computer.
I haven't yet found another MorphOS user who has been able to run it.
