Thanks MaG and Marion!
@Tally Ho - that's really useful feedback, thanks!
I'm not sure what I can do about the size issue (the resolution is stupidly low by modern standards but I just love working with 320x200) - apart from suggesting running it in a window if people have a small monitor. Originally I was going to use all extremely simple graphics (from another children's educational game I'm working on concurrently), but the temptation to get the Trolls and Captain Disaster into the mix proved too great...
The colours issue is tricky. Until a few years ago when working on A Playwright's Tale and in a discussion with our amazing artist about the colour in some of his backgrounds, I had no idea that the saturation appears so differently on different monitors. The colour differences I've used look very obvious on my screen. Could you let me know which one(s) don't appear too different on yours?
I have no idea why that bug appeared. The game was compiled using AGS run on a 32-bit system, but AFAIK that should make absolutely no difference. Please let me know if it recurs and when it happened / what display settings you were using.
Thanks again for your feedback, I really appreciate it
I've also added the demo to Itch -
http://captaind.itch.io/spot-the-difference - which atm has 4 screens compared to 3 on GameJolt (will update both with more soon - now that I've done a few screens I've got a lot faster at adding them!).