I agree Vulcan games looked like bad PD-quality games. They insisted on releasing a500 floppy disk games when absolutely everyone was using hard drives, tons of fast ram, aga or rtg and accelerators. These looked like they were done with AMOS.
Heheh, that's because they actually *were* done with AMOS ;-)
I see Rise of the Robots is hated, I must disagree though. It's one of the better Amiga beat-em-ups and one of the few games I actually bought, and I still play it regularly. Admittedly the disk swapping was annoying when playing from floppy, but that's pretty much unavoidable with a 880K DD floppies, and not really a fault.
In terms of bad games, maybe the Amiga port of Armalyte would perhaps qualify as one of the worst, it's absolutely awful. So is Hostages.