I only ever tried it on my A4000 so I guess it was opening in an AGA screenmode. I'll try it on another machine with rtg (i.e. A2000).
@Jose
As for clickboom, I'm glad they did as many games as they did but they seemed to always fall short on playability. Myst simply isn't my cup of tea anyway but their 68K Quake port was dreadfully slow (there's no way I'd use it over Frank Wille/Steffen Hauser's port or BlitzQuake). I do applaud they for doing it and I still want to some day try Capital Punishment. I've read though that other games like Napalm, etc. are like old Psygnosis games, big on upfront presentation but low on speed and enjoyment. imho, hyperion is/was doing a better job at porting games to the Amiga (cheap plug here).