Found this proto of Maui Mallard for GB and can't find any information on it whatsoever. Can anyone help me find a value for this? Thank you

Cover those EPROM windows up with non transparent tape (electrical tape, stickers, whatever)

Have you played the proto? Is it identical to the retail release, or are there differences? From what I've seen, differences and popularity are the things that determine the price of the prototype, though I'll let the proto experts chime in with that sort of thing

Honest question:

Almost every time someone asks me about a prototype they found they say they can't find any information about it online. I'm just wondering, what kind of information do you expect to find on the internet? I never know how to answer these questions, other than to explain what a prototype is. Is it just the value? If so, I'd guess somewhere in the $50-100 range on eBay.

Does it work?

Just tested it out and played through level 1 and it's a pretty cool game.