OK, after the absolute banger list that was 1986, this feels like a let down. A lot of second titles in the series. Of this list I played nethack a lot and had a lot of fun. But in regards to importance, it is just one roguelike, although maybe the most well-known. Maniac Mansion is also important, as the first LucasArts adventure and bringing a big step in adventure games. But it is neither the first adventure, nor the first graphical one. I am not well-versed in the world of beat-em-ups and shmups, so I cannot say much to Contra and Double Dragon. I heard of both, so they are probably important, if even I heard of them.