Thank you for this info.
Could you please tell us exactly which "Willy spin-off games" struggle on the Vega? And what you mean exactly by "struggling"?
There are 3 basic types of JSW game engines in existence: the original one (48K, nowadays often referred to as JSW48) and John Elliott's engines developed from the original one: JSW128 and the more advanced JSW64, both 128K. Among the JSW48 game engines there are also modified variants, such as the so-called "Geoff-modes" (1 & 2) and "Erix1-mode".
I see no reason why a game using an unmodified JSW48 game engine should behave any differently on the Vega than the original JSW or Join The Jet-Set!. If the original JSW works fine, they should work fine too. I would not be equally sure concerning the modified JSW48 engines and the JSW128 and JSW64 engines, although I would give it a 99% probability that they should behave exactly as they do on emulators, i.e. work just fine. This said, I am not referring to the use of joystick, because I have no experience with it using emulation.
I keep a list of gamma-released MM and JSW games, cathegorised by the game engines they use, on JSW Central.
A few of the JSW spin-offs I've tried don't appear to load up correctly. I can't exactly remember which games now, but I remember one showing a loading screen, then locking up. Another shows a loading screen and then resets itself with the usual black square/white border flash, and then back to the original home screen (1982 Sinclair Research).
I must admit, it was nice to see that reboot again though. It immediately brought back endless memories of trying to load games, waiting patiently for 5 minutes before seeing that black and white flash.
I'd also give anything to see another `R Tape loading error' message too.....