What games have you played where the developer didn't just stop at making an amazing game, but they really went the extra mile? Either the game had far more content than you expected or little details that would hardly get noticed.

For me the games that come to mind are Resident Evil 4 for the extra modes and huge amount of content, Bayonetta 2 for the same reason, Metroid Prime for detail and probably GTA San Andreas because there's almost too much to do. 

The mix of Super Mario Galaxy 1 & 2 since the latter was originally meant to be a mere expansion to the first, but just ended up too big not to release as a standalone product. Each game contains like 15-30 hours of fun.

Skyward Sword is also massive. People constantly attribute its value to its length and span of content.

Dragon Age Inquisition is the most recent for me. Completely redeemed what BioWare did with DA2 and is easily my GoTY for 2014.

The Mario Galaxies, gosh, these are fine examples of game design at its best!

Burnout paradise, the dlc, both paid and free expanded that game above and beyond what it originally shipped as.

GTA5. they just went crazy adding stuff in that game, whether i liked it or not. it was a really great game and i feel they went the exrta mile.

Resident Evil 5!

Resident Evil 6!

DriveClub. Tons of tiny details and the huge after launch support brought with it free cars and major gameplay changes. The weather patch alone added a huge visual boost to an already unbelievably realistic game. Photo-mode added tons of replayability for those looking to capture every tiny detail. Rainbow.s are realistically generated in realtime taking the suns position and rain position/density into account. Heat haze (which also takes the suns positioning and the environments temperature into account) was also added in the latest patch further seating the visuals in reality.The AI was tweeked so they don't reach ridiculous speeds drafting off players and other opponents. Crash physics bug fixed. The online was also fixed fairly quickly looking at other 2014 releases (though it should have been working at launch).

Honorable mentions include Uncharted 3, Ratchet & Clank: Into The Nexus and Donkey Kong Country 3D.

I would say Starcraft : Brood war from blizzard.
From what i recall the last patch came out in 2009, 11 years after the games original release.
Plus the original Bnet servers are still up a full 17 years after the game came out letting you play online free.

Newer games it is harder to select due to all the DLC garbage that comes out nowdays.Going back 15 years maybe Shenmue.