Heck, look at half-life 1 & 2. Both had some really great single player experiences that were revolutionary for the time, and when they came out, they were packaged with a rudimentary multiplayer, but think about the added value you got out of the multiplayer package over the years. I was still playing multiplayer mods of half-life 1 six years after I bought the original game. I doubt Bioshock 2 will have that much value, or be modable, but an interesting multiplayer mode could be fun.I've beat Bioshock once, but never really felt compelled to go back except to look and see if moving to Directx 10 made any appreciable quality difference to the game, since my first playthrough was on XP, and now I'm on Win 7.