It really depends on the game series, and the circumstances surrounding my playing it in/out of order. I don't presently have an XBox 360. As such, I never played the original Dead Rising. But I really wanted to play the game because it looked like ridiculous fun and I'm just a huge zombie nut, so when I found Dead Rising 2 for the PS3 on sale, I jumped right in and didn't much care that I missed everything that happened in the original. While I'm sure I missed little callbacks to the first game and didn't have as much context to the story in the sequel, I still found it a thoroughly enjoyable game. Of course, it helps that the game/series doesn't really have the deepest of stories. Another example is Resident Evil. I played (or tried playing, I should say) the first and second. Never beat either of them because I couldn't stand the clunky controls and, quite frankly, found the point-n-click puzzle adventure aspect of the games tedious. Never played the third or any of the numerous side-story games. But I got right back into the game with RE4 and 5. Again, I probably don't get as much out of those games as the hardcore fans who've played every entry and know all the history and back stories of all the characters, but I didn't feel entirely lost playing those later entries. Or the Killzone series. Didn't play the original. Was only mildly interested in the second one, but never found it cheap enough to make me consider picking it up. But I bought and played Killzone 3 because it had a co-op campaign, and that's all I really wanted: an FPS that offered a co-op campaign. Not an easy find on the PS3. And, again, I was fine playing it out of order, because, again, there isn't really all that deep a story to the game - which I didn't much care about anyway. However, something like Uncharted or inFamous or Assassin's Creed or God of War? I absolutely felt compelled to play them in order, even though most people would likely argue that the first entry in each of those series is inferior to the second outing and could probably be skipped without losing much. But, for whatever reason, I wouldn't let myself play any of those games unless I played them all in order.