How in the world is this Wallace and Gromit? What happened to moon cheese and Shawn? I have a W&G clock, and even I didn't see this sort of pandering coming. Of course it'd be funnier if they stole the IP themselves, but . . . Yeah. I don't get why they bothered.
Beat and 100% completion three times now. As for criticism, I don't much like the dash control. Granted, for some laptops that only allow two keys to be pressed at once, there isn't much you can do about it, but the occasional fine adjustment turned into leaping off of a tower. Which is how I found one of the large gems, but that's neither here nor there. Also, you used the term McGuffin. Kudos.
-- For people having trouble -- First, buy skills. Hardy, Regen, and double-jump will make the nightmare so much easier. When you get level 5 in jump, fortitude healing, etc. then blow your money on hearts, and beat the nightmare. Until you can beat him, don't waste money on relationship, as it will go away.