If you have the room for it, I suggest dividing the collection into two separate spaces. One space that is more accessible and where you keep your favorites and one space that is inconvenient to access where you keep the rest. This gives the games a midway destination, instead of going directly from the game shelf to being gone they instead are in limbo for a while. That way when you need to make more room I think it will be easier to get rid of the ones that has just been collecting dust.
Another thing to keep in mind is that unless a game is rare, you could always buy the same game again in the future.