I'm skeptical that a market consisting of products which range in price from free to one dollar requires sophisticated discovery systems. Most mobile games (and virtually all web games) are free to try - there's no need for social proof.

This is the reason casual game reviewing has never been anywhere near as valuable as in the traditional market. People just don't need to read a review about a free game before trying it, they can just sink 5 minutes in and see how it is.

The other aspect of this product is also underwhelming; the check-ins. You're essentially trying to gamify... well, games. A good game will have more than enough intrinsic rewards that layering these extrinsic ones on top will add little value in my opinion.