Strange that it was declined, it should certainly be possible. A slew of Steam games (Wolfenstein II, Prey, Metro Exodus) were just ported to the Windows Store and the existing trainers work fine there. In theory this shouldn't be different.
Superhot is different; it uses Microsoft's UWP and is much harder to code for. We're just lucky that the developers ported some Steam versions of their games to the Windows Store for the Game Pass for PC. Not all will be like that and plus Superhot was added way before the Game Pass for PC thing existed.
[Edited by Rhark, 6/25/2019 12:07:30 PM]
Is there a reason why it keeps getting declined?
I think at first it was because it was too complicated or something but now it's on the Game Pass i'm not sure if they'll make one or not - I know at first we were told that they would be working on Game Pass trainers and we've had a lot but there's still a bunch without trainers so I guess we'd need to ask the coders? 🤔