It's 250 eggs to unlock the final gallery piece.It's a bit of a challenge, but I personally think it's worth it!
good news
I've beaten it!
but the other gallery thing hasn't been unlocked tho,just the disgusted and the end scene
Hey good job!
The other gallery images should get unlocked as you see them in game. Basically you'll have to "fail" at each level to get all of them. If that doesn't happen then something's wrong, in which case let me know!