I think far too many people don't understand what replay value is... first off it is not the continuous playing of one character to the end that is never reached. Thus, playing one character on Skyrim for 500 hours is NOT replay value.
Multiplayer is also very rarely replay value-justifiable, else Halo is the most replayable game.. and anyone who wants to say it is needs a lobotomy immediately.
Replay value is what makes you come back to the game after you're done with it... and for how long it can sustain you, either for another whole session of 20- 30 hours or 4- 6 hours, or for 6 more times that year for those hour scale periods.
Portal 2 was a good game, but did it really have replay value? Outside of some of the short short dialog, did anyone truly desire to go through the exact same puzzles again? Especially the ones outside of the primary complex? I would say most people liked the game but didn't want to go through the puzzles immediately after. So it has short-replay value beacuse it was enjoyable, but it has nothing to make you drive through those things again for no other reason. While it has a multiplayer system.. again that could be considered after the SP you play the MP Co-Op.. okay that's done.. any reason to keep playing tomorrow? Nope. Well then, time to insert the FPS I'm addicted to (addiction is not replay value) when I get back from school tomorrow and after getting high like the waste of life I am.
Dragon Age was a great RPG, though it didn't fit Baldur Gate entirely and so many were upset with it, and then because it tried to they were upset with it, and then others were just upset. Did the DLC bring people back? It was intended to and to some it did. Did it have multiplayer? No. Did it have an additional public content creation system? Yes, and that brought some back, but it wasn't the game becoming replayable, it was a modified version of the game, thus the game itself wasn't part of that replay value because the DLC was primary and direct content from the developers, but what was done after were just modifications. Did the story make you want to try different things? Well to be honest it doesn't change all too much but yes it did. So Dragon Age has replay value, though I'd say more to a short degree of 1 more time and then a few more times every other year.
Does StarCraft have replay value? Well it has Custom Maps which are an attempt to be lazy by Blizzard and have users make their game replayable but not through mods that have to interface with it in complex ways, but through the map system itself which is direct. So they take credit for it, but excluding that and the addicted / competitive content which to many is just the game itself (though SP for me) and thus not replay-value because they aren't replaying, because they never really finished what they view as the primary game in the first place. Does it have a campaign? Yes, but outside of difficulty modes which are a sad attempt at replay-value methods without any insight, creativity, or depth.. it doesn't have much that makes someone want to go through EVERYTHING again right after it. So StarCraft's replay value both 1, 2, and the coming expansions are based on difficulty levels (PAH!!!!) AND custom maps, which sadly is a cheap way on Blizzard's part to not actually do anything.
So what has real replay value? Things with customizations, multiple ways to play through the game, and RPG elements usually have replay value. An example is the MechWarrior series with all its customization, or a trading card game with all its customization. Replay value continues because there are numerous ways to achieve the same result. The problem being that high-replay value needs to get people to want to go through that again, and that's tricky.
So to be honest.. any multiplayer focused game can't really claim replay value because to many that's just the primary part of the game, and replay means what brings you back and since many people are going for the highest levels or customizations unlocked.. that usually means they are still in the primary game thus aren't replaying... it's the people that get bored of that and then leave... which brings in the term replay-value, because whatever gets those people that left the game, either after, or during the campaign, or during the multiplayer competitive leaderboard stretch.. is the real determinate of replay value.
Art can be one sometimes... Story can be for a bit, but eventually even story can get overused in certain games.
So yeah... replay value? That's extremely rare.
