@Grauw: Nope, tried the advanced search and there is an option for max_players:2 but not something like max_players>1, so you have to do several passes.
Unfortunately the information in the DB on Max Players, Max Simultaneous players and Controllers is not the best... For a lot of games the information is missing, or simply incorrect. I have made a few updates based on this thread.
The trick is to do an "empty" search, then select the category your interested in (e.g. software), and then on the left hand side you can set all kinds of filters.
