Games you've played so much you have them completely memorized

I can tell you where every hidden room is, the location of ever weapon and ammo dump, and where exactly on the map every enemy spawns in Max Payne 1 and 2.

I could also probably run through Link's Awakening blindfolded at this point.

Most of the multiplayer maps of Command and Conquer Renegade. The single player of Command and Conquer Red Alert 2. Most of Pokemon red.

Pokemon Ruby is the only game I can do super fast. 8 hour speedruns, like a boss.

The original Legend of Zelda. I talked someone through that game over a phone while reading comic books.

Zeno clash I know where every fruit is and weapon and silly little background thing.

Halflife 2 and Portal (easy to memorize because there's so little dialogue and my average playthrough is 40 minutes), but I'm more proud that I memorized everything, including just about every line of dialogue in every cutscene in Metal Gear Solid (my favorite game of all time).

THUG.

I can play Home Alone 2 for the NES without ever getting hit, I know it's a bad game but as a kid I would play even the worse games and like them and this one I could finish in less than an hour which I did many many many times. I know Prince of Persia Warrior Within pretty good, I know where the life upgrades are, I never get lost and know all the strategies to the bosses(finished it like 12 times).

THPS 1-3, Pokeman red/blue, GTA3.  Mostly.

Ocarina of time yes, even the dreaded water temple it took me a couple of times but i literally knew where everything was at and what to do.

I just finished my third playthroughs of Alpha Protocol and Dragon Age II, and even if I may not have them memorized completely, it sure feels like I have.

CAN'T LET YOU DO THAT STAR FOX

Pokemon Firered, ANY kirby or zelda game .

Kirby's Dreamland. Know that game front to back. Also Dj Hero, but that doesn't count i guess.

Contra (NES), all three Donkey Kong Country games (especially 2), Return to Castle Wolfenstein, Jedi Outcast, Portal.

metroid fusion. I can play through it in like 2 hours

Final Fantasy IX. 

" CAN'T LET YOU DO THAT STAR FOX "

Tony Hawk 3

Final Fantasy X. Not everything. But a lot of it.

I would say Morrowind as I have many hundreds and hundreds of hours put into that game, but every time I replay it I find something new. I never finished most of the factions and haven't entirely finished the Thieves Guild. 

Sadly I could adapt the story of Shenmue 1 and 2 into a novel just from memory at this point.

Prince of Persia: Sands of Time - Warrior Within - The Two Thrones and of course Super Mario Bros.

Duke Nukem 3D

Fallout 3.

Dead Space 2, especially after recently finishing it on Hardcore.

I can tell you how to finish every quest or how to get anywhere from where you are in Neverwinter Nights.

Final Fantasy 7 and Sonic 3

Pokemon Yellow, Uncharted 1/2, Half-Life 2, Metal Gear Solid. 

In terms of city layouts, GTA III and Vice City. I can visualize getting from almost any point to any other point.

No one now, but back in the day I had a knowledge of Resident Evil 2 superior to most. 

I somewhat know Sonic 3 and Knuckles of by heart kind of, but im more familiar with the first part of Sonic 3 and Knuckles i.e. the Sonic 3 part lol, the super emeralds in the Sonic and Knuckles portion still baffle me sometimes

I've 100% completed Vice City 6 times. I don't even need a guide for hidden packages or stunt jumps.

Mass Effect 2

Burnout Paradise. I know that city like the back of my hand. Same goes for Burnout 3: Takedown. I remember when and how to drift around corners, as well as most of the traffic patterns.

Diablo 2

Too many.  I will just toss out all three King's Fields released in NA.

Full Throttle

All the multiplayer maps for Call of Duty W@W and MW2.

Halo CE 

i like to think that i've played Max Payne enough times to have it memorized by now

probably metal gear solid or final fantasy x.

Shinobi III:Return of the Ninja Master. Know absolutely everything there is to know about that game.

Tron evolution

I know alot about Unreal Tournament, especially 2004. Like item placement, damage numbers on the different weapons and attacks (I did the math on how much opponents have left), respawn times etc.