i always get an ich to play infamous every few months. Also sc2 owns my life so theres that too

Yes i recently went back and played some Onimusha 2, Morrowind, and Rogue Galaxy. I use my PC to emulate my ps2. I just put my old discs in and viola.

I've completed MGS1 a few times. Does Counter Strike Source count as an old game (2004)? I also play some CoD4 multiplayer from time to time. Most games I just complete them once and I'm done.

I still play Warcraft 3, Starcraft; Brood War, Smash Bros Melee, and Smash Bros 64.

Their replay value is infinite. They are, coincidentally also the best games ever made. A single one of them beats out the entire PS2 library in my eyes, because they'll bring me more hours of enjoyment than the entire game library.

EDIT: Heroes of Might and Magic 3 is of course also one of those games.

I play through the Spyro the Dragon trilogy at least once a year. Normally it takes me that long to forget about them, then I put them in again and just have a blast. Crash Bandicoot regularly gets replayed, too.

I've also rebought a few HD Collections to play through again, and they're the type of games that I'm going to be playing far into the future, too (i.e. Jak & Ratchet).

Command & Conquer games often get revisited by me (particularly Tiberian Sun), as well as Age of Empires 2.  The Sims 2 as well.

Plenty of stuff other than that: I revisit SSX 3 often; Final Fantasy VII and VIII get multiple play-throughs; Future Cop LAPD is a game I often re-visit; Populous: The Beginning; any old WipEout or PS1 Ridge Racer title.

Long story short, anyway: yes. I love revisiting old games. I don't even consider early-in-this-gen games old enough to have been "revisited" yet.

Yes absolutely. Honestly, the system I revisit most, is the NES. Those games, for me, just have a timelessness and replay value to them that just has "Something" to it, where you can go back and play them anytime, and still have fun. Whether it's Super Mario Bros., or Kirby, or Metroid, or Mega Man, or Castlevania, or Contra, or TMNT, Double Dragon, Adventure Island, Star Tropics, Mighty Final Fight, Tetris, Yoshi, Crystalis, Ninja Gaiden, etc. etc. etc., a lot of those games are just awesome to me. They just have something to them that I find a lot of modern games lack. SNES/Genesis era would be a close second.

But in general, even for my PS2 or Wii or whatever, sure, there are games I come back to from time to time. It simply matters what kind of game it is. I personally find, that a lot of modern games are made with a story in mind, and/or graphics, over gameplay. Which tends to lead to gamers (myself included) playing through them once to see the story, and then rarely ever touching that game again, or even trading it in. Whereas, obviously, the games that I would come back to over time, have gameplay as the bigger focus, and are thus more fun to play, and thus I come back to play them.

As for the question "how much replay value can a game have?" Honestly, the answer is a shit-ton, depending on the game. I can go back and play old school Pac-Man anytime. No problem. I cannot, however, just pick up, say, Prince of Persia: Sands of Time and play it whenever, because it's just not the kind of game you can pick up and play anytime. Not to me anyway.

Not much. Only Elder Scrolls and every three years or so I go back and re-visit Age of Empires 2 online for a time.

I occasionally go back and play all the GTA games and they never get old to me, but other than that i don't normally replay anything. I have so many games to play as it is

The original Super Mario Bros' replay value is infinite. Mario Kart, SSB are near infinite.

I still play 2-3 playtrough of digimon world per year, 13 years after it came out.

Replay value : infinite