From Wiki - GameHacking.org
With all of the code requests out there, it's hard to remember what still needs to be hacked. Inversely, sometimes it's hard for hackers to think of anything new to hack. Shouldn't there be a place where all the relevant code requests around can get together in one big, whopping page? Nope. But now there is.
Romance of the Three Kingdoms
Recruit Generals Always Succeeds:
Romance of the Three Kingdoms 2
Hacked by Darkmoon2321
Sell Rice Command Doubles Gold and Rice:
Switch Sides Always Succeeds
Tiger-Wolf Always Succeeds
Forgery Always Succeeds
Rival Tigers Always Succeeds
Recruit Always Succeeds
Threat Always Succeeds
Shingen The Ruler
100 Gold Mines (Japanese Version)
At the game menu, pick the second option from the second row. Then select the 1st option, choose 0000 and highlight "Yes" (first option). On controller 2, hold Left-Down + B and on controller 1, press A. If done right, the gold mines counter will increase to 100.
Contributed By: ReyVGM
Climate Disasters Don't Affect You
At the game menu, select "Sv" and highlight "No". Now, on controller 2, hold Up-Right + A and press A on controller 1. If done right, you'll be able to move your troops and call the merchant even during snowstorms and typhoons.
Contributed By: ReyVGM
Final Fantasy II
Level mod per character slot
Do Danger Moves Anytime
Hacked by Abystus:
Killer Instinct v1.0 (U) Enable Finishers During Round (Even works in practice mode.) 4083-3DAD 4083-34DD 408E-3D6D 408E-346D AB8E-37DD Killer Instinct v1.1 (U) Enable Finishers During Round (Even works in practice mode.) 4083-37AD 408E-3FDD 408E-376D 408D-4F6F AB8D-44DF
Advice: Judging from some text it says there is a Test Grid Course or something like that. It will require the method used to find Banjo-Kazooies test course, as the regular course modifier doesn't show it.
Have Levels Open
Enable Code (Must Be On) DE000400 0000 8124C9D8 1000 812876A4 1000 812D3DC0 2400 Gain access to levels (replace ?? with level number) Level Entrance 80383301 00?? 01 - Mumbo's Mountain 03 - Clanker's Cavern 04 - Bubblegloop Swamp 05 - Freezeezy Peak 06 - Gruntilda's Lair 07 - Gobi's Valley 08 - Click Clock Wood 09 - Rusty Bucket Bay 0A - Mad Monster Mansion 0B - Spiral Mountain
Enemy Health codes
Advice: Crocc hacked the Greece vehicle mod. Are there vehicles anywhere elsewhere in the game?
Play As The Sub-Bosses [Might be possible]
Costume Bomber P1 In 1P Mode [Impossible]
Command & Conquer 3-D
Change The Color Of Your Side
No Fog On The Map, Change The Fog Color
Change The Cursor Color
All Terrain Revealed
No One Dies
Fast Air Attack
Conker's Bad Fur Day
Diddy Kong Racing
Advice: Quite possible but needs ASM work. The game keeps all your speed, bananas and other shit in different places depending what vehicle you use, what track you're on, and possibly what character you use. I made an Always 50 Bananas code a while ago (not sure it's in the archives) but it only works when you're in a car, I only tested it with one character, and I couldn't get speed to work because of some weird addition bug.
Enable Code (Must be on)
Activate High Speed Racing Cheat
Stop/Extend timer when things are moved/opened by a switch
Play as Gezorr
Play as Secret Characters in Story Mode
Earthworm Jim 3D
Moon Jump / Jump Height Modifier
Hacked by Nolberto82:
Hit Anywhere P1 810FA5DC 0C0F 810FA5DE FFF8 813FFFE0 0085 813FFFE2 602A 813FFFE4 1180 813FFFE6 0002 813FFFE8 8D04 813FFFEA 0000 813FFFEC 23FF 813FFFEE 0074 813FFFF0 03E0 813FFFF2 0008
Hacked by Nolberto82:
Disable Blocking Both Players 810F8368 2400
Everything Is Opened Up [Battle Mode, etc.]
Proper Character Modifiers (not select mods)
Fox Sports College Hoops '99
Play as Secret Teams in Season Mode, Full Court Dunks
A way to get around the goddamn TLB mapping and dynamic ASM locations
Throwing Knives - Throw Distance modifier
Watch Lazer - Laser Stream Distance modifier
Timed Mines/Grenade - fuse modifiers
Fixed Moon Jump (Cannot actually "jump" unless you are moving down a slope)
Disable Random Guard Spawning
Knockout Kings 2000
Hacked by Abystus:
Hit Anywhere (Both Players.) 810B4EF4 2400
1-Hit Injures Players
Change Tiny Huge Island from one size to the other on demand and/or modify how tiny/huge it gets
Advice: Pretty sure the two islands are two different level models, so scaling is probably impossible, and switching on demand would be a bitch to do.
Bomb Size and Existance Modifiers in Bowser fights
Walk Through Walls code that doesn't kill Mario when you go through a wall
Advice: The game just kills Mario when you're outside of the level model. Not much that can likely be done about that.
Freeze timed steps on Bowser levels
Modify the speed you go at while carrying that big bom-bomb
Advice: I think the run speed mod effects this, but I haven't tried it. Too much COP1 shit to look through.
Bomb-omb fuse timer/explosion size modifier
All coins are red/blue?
Penguin/Koopa speed modifier
chain chomp speed/chain length modifier?
Advice: Where you end up when you get killed or exit a level. Preferably, make it so exiting from the pause menu drops you in front of the painting like it should, and leaving the Cavern of the Metal cap puts you back at the entrance to Hazy Maze Cave instead of dropping you out the damn waterfall.
Flatten enemies besides Goombas
Modify enemy health
Advice: i.e. Make Goombas harder to kill.
Multiple jumping while holding an enemy
Modify how many stomps it takes to drop posts (chain chomp's)
Starting points inside specific levels.
Advice: Like starting at the warp to Bowser in each of those levels all the time, or even changing that location.
Tiny Huge Island boss health modifier
Tree/pole climb speed
Mario Kart 64
4WD (No slowdown offroad)
Turtle Shell Throw Speed Modifier
Always have 3 shells spinning around you (Shell Shield)
Blue shells shield you like Red shells (three around you, and you have an infinite amount of them)
Double Dash!! Point System
Advice: (5th-8th get points, change 1st-4th point amount)
Slower Response Time / Faster Response Time
Advice: The computer recovers quite quickly (Lakitu responds more quickly) after a crash or fall. This is unfair!
MLB Featuring Ken Griffey Jr.
All Trades Accepted
Pick whole team in draft before anyone else
GS button For Homerun
Change Statistics After Game
Computer Doesn't Swing
Mortal Kombat Trilogy
P2 Can't Move
Play Hidden Space Invaders Mini-Game Easily
Mortal Kombat 4
Advice: MK2 had a soak test via codes, it was a showcase of fatalities. MK4 has text for one...all it says is "SOAK Test" in memory might still be hackable.
Mortal Kombat Mythologies - SubZero
Infinite Fatality Time
Once Frozen, Enemies Never Thaw
Full Invincibility from traps
Advice: Some have been hacked, but I'm pretty sure there are a few remaining because of some evil programming.
Full Court Dunks Sink Every Shot (like from full court)
NBA Jam '99
Enable All Trades
All Objectives Complete / Never Fail
Hacked by AKUMA 2002
Rapid Fire Farsight 8106E085 0000 8006E081 00FF 8106E01C 0000 8106E05C 0000
Enemy Character Modifier (not an image mod) Icon Modifier List
Fixed Moon Jump (The game kills Rayman if he is in the air too long)
Jump Distance Modifier
Advice: There's Infinite Boost, but that can't slow you to a complete stop and you can only go so fast.
Star Wars Ep1 Racer
Hacked by Dlevere~The Hackmaster
INFINITE BOOST Leave your opponents choking on your dust as you speed through the levels with this incredible code! 81226D66 FFFF
Star Wars Rogue Squadron
Advice: When you press pause and text search for "Debug" a lot of Debug Menu stuff is shown that would be good to see usable.
Star Wars - Shadows of the Empire
Easily kill enemy riders in Mos Eisley
Enemy Character Modifiers (Wreck hacked some for Echo base)
Control any enemy codes
Ship modifier for Asteroid Belt
Dash Rendar Character Modifier
1P Mode Level Modifier
Infinite Turbo Boost (MP)
Infinite Shields (MP)
Top Gear Rally
Speed Modifier (one that actually works)
Vehicle Stats (acceleration/max speed)
Special Cars in Paint Shop
Advice: There is an Airplane in Coastline and Jets that fly over in Strip Mine)
Turok Dinosaur Hunter
Run Speed Modifier
Climb Speed Modifier
Allow monkeys to be hit by weapons besides the Particle Accelerator
Remove screen flash with Chronosceptor
Turok 2 - Seeds of Evil
Fixed Moon Jump code
Moon Jump Without Expansion Pak [Note 1]
Moon Jump With Expansion Pak [Note 2]
Note 1: This code is for single player mode without the expansion pak upgrade. Hold L to rise, release L to land.
Note 2: This code is for single player mode with the expansion pak upgrade. Hold L to rise, release L to land.
All guns can blow off heads/limbs
Run Speed Modifier
Advice: There is some text alluding to one.
Turok 3 - Shadow of Oblivion
Unlock/Identify mystery cheat in the cheat menu
Advice: There is one cheat that's never revealed by the All Cheats code.
Advice: Lots of debug text in this one: Secrets.Enter New Secret....Control Options.Debug...Display Options.Turok 3.Shadow of Oblivion..Select Difficulty...Select Language.Select Deathmatch...Sound Options
also shows at: Resume..Save Game...Load Game...Options.Secrets.Quit....Quit game...Replay section..Replay chapter..Cancel..Quit game?.......... remaining..No time limit...Objectives:.Deaths..Sound...Display.Control.Debug...51..NTKP....TUROK
Enemy codes (size, image, etc)
Advice: ASM will be required, since the game is so random in RAM allocation.
Turok - Rage Wars
All Characters Unlocked
All Campaigns for All Characters Unlocked/Done
Stop Fatality Timer
Hacked by Abystus:
Hit Anywhere (Both Players. Excludes Projectiles.) 812F3878 1000 812F4218 2400 812F433C 2400 812F438C 2400 812F43F0 2400 812F45F8 2400
Wayne Gretzky's 3D Hockey '97/'98
Every shot goes in / remove goalies?
Hacked by Nolberto82:
Wayne Gretzky's 3D Hockey Score From Anywhere(Press R) D20BC1A9 0010 8105C3E0 1040 D00BC1A9 0010 8105C3E0 2400
Wayne Gretzky's 3D Hockey '98 Score From Anywhere(Press R) D20D1FA5 0010 810606D0 1040 D00D1FA5 0010 810606D0 2400
Hacked by Dlevere~The Hackmaster
Hold A+B for Infinite Boost Tap B while holding A for Machine Gun, Autopilot, and Stealth Mantle! 810CBB83 FFFF 810FCAC3 FFFF
Call-In Other Wrestlers Manually
WWF No Mercy
Infinite Rematches in Season Mode
Too many codes to be listed here. Over 400 codes hacked by drgonzo7 for this game. 
Workable Big Key
Can Ride Epona Anywhere In The Game
Epona Can Walk In The Water
Link Gets Ganondorf's Horse
Sandstorm in Haunted Wasteland Is Gone
Sandstorm Mode (Sand Flying Everywhere)
Blood and Gore Mode: Anything You Hit Spills Blood
Underwater Mode (Underwater visuals/SFX)
No Background Code
No Objects Code
Can Use All Weapons Underwater
Mess With Texture Cache
Zelda: Majora's Mask
Game Boy / Color
Game Boy Advance
007 Quantum Of Solace
Max Upgrade Points
No Clipping (Select+Up)
Clipping ON (Select+Down)
Slow Motion (Select+Left)
Normal Speed (Select+Right)
Display Collision Boxes
Universal Key (press Select on menu)
Golden Gun (Press Select on menu)
Body Armor (Press Select on menu)
GF-17 (Press Select on menu)
P-99 (Press Select on menu)
Mac-11 (Press Select on menu)
AK5U (Press Select on menu)
M14 (Press Select on menu)
All of these codes have been hacked on the European version of this game, but not the US version. When I tried to convert them, they didn't work.
Fossil Fighters: Champions (U)
Golden Sun: Dark Dawn (U)
No Experience Points Gaine
Ram Racing (E)
Always 1st Place
The Adventures of Batman & Robin
Advice: The hit anywhere part is easy, but certain bosses have a weak spot as their only attack-able area and hitting anywhere else on the boss nullifies the hit anywhere aspect of the code (they become un-killable). Need one that enables said weak spot to be attacked anywhere.
Power Stone 2
Character modifier for players 1-4
Game Shark Codes
|Unlock All Items||C7EAB038|
|Infinite All Items||A642064E|
|Unlock All Materials/Essences||D059D41F|
|Infinite All Materials/Essences||BED76D52|
|Unlock All Text||759484C2|
WWF Royal Rumble
Advice: The original code never seemed to work in the actual Royal Rumble mode but worked at times in 1P/Arcade(?) mode. I'd say an ASM hack is likely needed.
Castlevania: Symphony of the Night
Boss level mod
Boss HP mod
Boss defense mod
Boss attack power mod
Command & Conquer: Red Alert
Enemies cannot build
Advice: using spies, watch what one enemy is building in a specific barracks, war factory, or other building unit. Find the difference between nothing, something, and something else. Now move on to the next building of the same kind, of the same enemy. Once you've found the address for both of these, find the difference between the two, and adding or subtracting it from one of the two, find the addresses of the first five of that kind of building that could be built. Now do the same with another kind of building, for the same enemy, and so on. Once you're finished with all buildings, start on another enemy. With any luck, after the first building of the first kind, you'll be able to find the difference between it's address and that of the corresponding code for the first enemy, and use that base to find all codes for that second enemy. Now use that difference to do the same for the other two nations (might as well include yourself), and you won't even have to do all the footwork. Still quite an undertaking though, for those with limited time.
Dragon Ball GT - Final Bout (Japanese)
Always Have Weapon Drawn (Arcade Mode)
Final Fantasy Tactics
Zoom/View mods in battle (helicopter view, etc)
Final Fantasy VII
Allowance of targeting
Advice: hack a target mod, hack hand there/not there, use increments of positioning with a D0 set up to turn the hand back to the first character once it reaches a certain character, possibly set also by the number of characters.
In-town character mod
Advice: I've noticed that there are a few interesting digits for Liquid Man's world map character mod.
In-town character mod - 8009D390 ????
0300 - aeris in town, can't exit, tifa on world map
0200 - Tifa in town, can exit, tifa on world map
0400 - Red in town, can't exit
0800 - Cid in town, can exit, Cid on world map
This won't help much for a town-specific code, but it may lead to an even better universal code that doesn't depend upon which sprites are available per room.
Emerald weapon in ocean/not in ocean
Other Weapons' existence on world map mod
Other chocobos are slow
Advice: find the difference between the times when another chocobo is going fast, and those when it's going slow. A sprinting/not sprinting code might also be nice.
In-town character size mod
Advice: using different rooms and utilizing the sprite control code, note which characters are which character number. Being sure to include at least one room with a large character (such as the giant Aeris in the very bottom room of the debug room, or the giant Cloud within Cloud's mind after he plummets into the Lifestream) and one room with a regular one, find the difference between character _ when that character is regular and character _ when that same character is big. If you can manage to do so with another character number, you could find the difference between the two addresses and by subtracting or adding that amount to one of the two, you could find the addresses of the sizes of all characters, including your own.
Current room chest content mod
Skip annoying parts of the game
Advice: Cloud's Coma sequence gets to be pretty mind-numbing after several playthroughs.
Unlock All Floors - Elevator in Shinra Building
Advice: Having the keys with the key items hack isn't enough for some reason. It might be hidden in the game progress flags.
Disable negative stat affects from materiaOdin always does Steel Bladed Sword
Advice: I've had some luck forcing the attack itself, but I can't bypass boss' and other enemies' immunity to instant death attacks for some reason. I found the address controlling the normal stat immunities for each enemy in battle, and posted those before. I found an interesting address that ended up forcing Steel Bladed Sword (3007136D 0005) when it would normally be changed to Gunge Lance. The problem is it chopped a boss in half, but it made it invisible instead of completely killing it.
Never Miss Any Attack/Magic/Summon in battle
Final Fantasy VIII
Away Team Scores 0
Home Team Scores 0
Legend of Mana
Boss level mod
Bosses/enemies cannot be stunned from constant attacks
Metal Gear Solid
Everything is white
Advice: using a stun grenade, find the difference between the times when everything is white from the flash, and when it's not. Note: I wouldn't have added this if it weren't for the fact that I hacked it once, but the game/system/GSPro crashed due to other codes that were activated, and I could never seem to hack it again. It was quite an amusing code, actually.
Metal Gear Solid: VR Missions
Advice: find the difference between the existence of enemies and their absence, either by beating the level or by killing enemies individually. The second option, however, could take longer, and might not even yield the same result.
Syphon Filter 2
No head shots
HACKED BY NEO ULTRA GAMER (NEO-UG) (Xeon)
No Headshots 30089EBC 0000
Final Fantasy XII
Rare Enemies Always Spawn
Advice: By "rare" we mean enemies like the Ripe Rampager and Level 99 Red Chocobo. They normally only spawn a certain percentage of the time and/or when certain conditions are met. Th fact the Level 99 Red Chocobo only has a 1 in 256 chance of spawning is bloody insane!
Any Car Can Race Any League
Drawing a dot in any part of the blockheads and they die instantly
Have Weapons/Unlock Weapons (on Tony or in locker)
This game requires an AR MAX 3.60 or above for the codes to work.
Final Fantasy IV The Complete Collection
Walk Through Walls
God Of War: Ghost Of Sparta
These are the codes that lee4 posted, converted to PSP Action Replay codes:
One Hit Kill
Size Modifier Codes
Super Small Size
Even Bigger Size
Speed Modifier Codes
Super Slow Motion
Orb Multiplier Codes
Disable Orb Multiplier Codes
All Skins Unlocked