Okay this is going to sound weird but i think it's doable and would be useful to some

ok so you'll have the option to add a (steam) game but it's cover art(s) will be grayscaled and instead of the usual "install/play" you will have "Purchase/Buy/Add to Cart" or something like that

another idea i had that i wanted to include along would be some sort of "complete/incomplete" tag for franchises for games who miss one or more mainline game (eg metal gear solid 4) or some other thing like a dlc (take for example dead rising 2's case west dlc which is xbox exclusive)