I answered Adventure to the poll, even though my "influential" game was Zork II. (The first
text adventure I played on a C64, one of the games that helped me a lot to learn English =)
This choice was remarkable for another reason: I was introduced to the concept of data structures that way. I wrote my own (very simple - only movement!) adventure games in BASIC, and I read from a book (forgot the author's name, again) how a network of rooms has to be arranged.
10000 DATA "The starting room", 0,0,2,0,0,0
10010 DATA "Another room", 0,1,3,4,0,0
Then the data was read to the arrays: first the string that had the name of the room, then the rest as directions where you can get from that room (0 simply meant you would get nowhere by going that way).
So, in a way, text adventures opened my eyes that hey, you can store game data somehow...
I never managed to write a working parser, though, but these days it might be quite possible... =)
-- Weyfour WWWWolf, a lupine technomancer from the cold north...