I don't actually think slotting fees for videogames in UK supermarkets are as common as people are suggesting. I'm not about to argue it strongly because I don't work in retail and people have a vested interest in shouting 'everybody does it' without examining if that's true, and if it is, to what degree.An article about that would be like writing an article about the local supermarket putting up a display for a Coca Cola endcap or a Best Buy putting up a cardboard display for the new Halo game. It's so day-to-day common that there's absolutely no reason to take any note of it. If a product's section expands noticeably after being a certain size (especially small) for a long time, especially if the expansion includes non-standard branded decoration, you can be sure the product's manufacturer paid good money for that promotional space and content.
Did you notice that this thread is based on one such article? It's hardly far out to have wondered if there was another similar article covering a competitors product.