Can I suggest some constructive criticism?

Can you implement Etag and the modified-since headers to return 304 not modified for some of the content like game thumbnails and such forth?

Can you move the search box to the top right of the screen and make it the same live results but in a div dropdown, then take the user to the game page on click instead of showing the prices? Edit: just realised there's no individual game page. I think that will be useful for users to see the price difference across each store, and maybe a historical chart to show as time progresses when it typically goes on sale (in case users want to wait until it's hit a certain pricepoint)

I'd prefer to have the landing page the most popular top deals instead of by store.

"Filter" has no semantic meaning on what it's filtering. Make it more obvious.

Any chance to make the redirect quicker? Maybe start a background thread (if that's fairly easy in PHP) if the majority of the processing time is recording the redirect. Maybe have a look at indexing on the DB too :)

Just my thoughts. Great job!