Replay value is "the entertainment value of playing a game more than once".

So what makes a game have replay value?
-unlocking secret features after the game ends (hard mode, extra missions, etc.)
-trying out a new "dimension" of the game (start with another main character, alternate endings, etc.)
-personal liking (the plot/music/gameplay suits your tastes)
-loyalty to a series (like replaying Kingdom Hearts while waiting for the next one to come out)
-striving for perfection (in games that make you collect items or that count your completion %)
-internet play (MMORPGs)
-multiplayer mode
-etc.

So here's my question to you:

Which game(s) has the most replay value? Give some explanation as to why, so that others might consider playing it!

I love playing all of my games over and over again.

Lately I've been playing some Mass Effect, though, and that sure has a high replay value for even those who don't replay as much as I do.

id say sonic dx since you can unlock all the game gear games to

Mmmm good question! My picks for games that have high replay value would probably be the Knights of the Old Republic games because um... your choices affect your character n' stuff. Yeah I know a really poor explaination, but trust me, they're really fun games.

Any Smash game, especially Melee.

the entire silent hill series.... ill play it until the end of my days.... all of it

Metal gear solid 1,2,and 3 . All those extra thing that unlock after you beat the game and trying to get new items. Like the new camouflage in Metal Gear Solid 3 or the invisibility in Metal Gear Solid 1.

pretty much every mario multiplayer game can and will be played over and over and over..... they are just so much fun!

even some of the mario single player games are addicting! Mario 64 is a classic, Mario Galaxy is incredible, all the NES/SNES games.... the list goes on!

Replay value wise...

Legend of Mana has story line in events and it is almost impossible to get 100% completion of all events without at least beating it once.

Saga Frontier has seven characters with different story lines and so it has seven playthroughs with special bonus at the end... Although, I've never seen the bonus...

Resident Evil 4 for the Wii is so entertaining much less getting extra things like Ada's storys and Mercenaries.

Super Mario Land 2: 6 Golden Coins...haha, once you finish all the madness, there's always that itch to start over again!

Yeah I didn't think of that one. Definitely Mario 64...I've played that a few hundred times.