You think is worth it $2 and I agree, but you can't charge any price because you're using Shrek's name and models. Shrek is trademarked by Dreamworks which means, if you're seling a product from another company, they could sue you for that... Unless you have the rights to publish a paid Shrek's game, you can't charge for that... You could easily get unnoticed with that, but the other problem is that your game is a big viral right now. Dreamworks probably knows your game exist.