Listed are games that have been tested on NES or Famicom hardware and verified to look wrong or odd, due to things like NES hardware limitations or programming errors. Refer to this if you're developing an emulator and find a game that looks wrong, before you look for a problem in your emulator. If you are attempting to give your emulator "bug for bug" compatibility, you'll want to make sure that these glitches (or unusual behaviors) appear the same in your emulator as they do on the NES.
This is an incomplete list that concentrates on commercial games. For an overview of common compatibility problems in homebrew games, see Program Compatibility. Sometimes, a bug slips into a game to make it rely on less-than-intentional features of the hardware; for those, see Tricky-to-emulate games.
|Akumajou Densetsu||When a door is opened/shut when the player goes through them, the screen shakes by one pixel.|
|Akumajou Special||After losing at the bidirectional scroll stages, sometimes the game over screen is glitched. (Validated in the Game Center CX)|
|Armadillo||The in-game status bar occasionally bumps vertically by 1 pixel. This game also often suffers from slowdown.|
|Castlevania||The PRG 0 version sometimes freezes right before the Grim Reaper. (Fixed in PRG 1 and PAL)|
|Castlevania II - Simon's Quest||Sometimes incorrect tiles are shown on the playfield.|
|Castlevania III - Dracula's Curse||
|Chip 'n Dale Rescue Rangers||After reading the intro to the last, garbage sprites will appear in the upper left (right) corner of the screen.|
|Commando||There are many bugs that may look like emulator glitches but aren't.|
|Crystalis||The scanline above the status bar and above text boxes looks wrong.|
|Dizzy The Adventurer||Resets the sound phase every frame, causing a nasty 60hz buzz.|
|Donald Land||When the player progresses too quickly by boosting off of apples, the background loads fall behind and the scroll seam becomes visible.|
|Double Dragon II||The status bar may suddenly change colors: sometimes when scrolling vertically it shows incorrectly for a couple of frames.|
|Double Dragon III||Same status bar issue as Double Dragon II.|
|Exed Exes||When pausing, the immediate next note of the music will play after the pause jingle completes.|
|Ghostbusters (J)||The Japanese version of Ghostbusters loads the ending text from the wrong CHR bank, causing it to display a blank screen that eventually scrolls the hiragana 'riri' on the screen.|
|Ghosts 'n Goblins||
|Hottarman no Chitei Tanken||If gameplay slows down due to excessive on-screen objects, scrolling may glitch and display garbage values.|
|Ironsword: Wizards and Warriors II||Noise channel doesn't work properly, sometimes plays longer notes and sometimes mutes.|
|Kirby's Adventure||When Kirby copies a new ability, the status bar icon may flicker or display incorrect attributes (?).|
|Legend of Zelda||The screen "jumps" off 2 pixels at the start and end of vertical fast scrolling.|
|Mega Man 3||
|Mega Man 5||In Gyro Man's stage, inside the two elevators, the floor moves up by a few pixels when the elevator goes up, and move back down when the screen is fast-scrolled.|
|Micro Machines||Graphical problems on PPU revisions prior to 2C02G due to $2004 unreadability. Resetting on Famicom and NES-101 doesn't always work because the game fails to clear $2000 and $2001 on reset.|
|Mitsume ga Tooru||Garbage data is visible in the upper side of the status bar by mistake when shaken by an earthquake, due to the status bar and playfield both sharing the nametables.|
|Panic Restaurant||The in-game status bar, always bumps up by 1 pixel.|
|Rad Racer||Steer to the far left, and a background scanline will be seen on the road.|
|Rambo||One scanline is occasionally glitched, for the same reason as in Super Mario Bros.|
|Rampart (Jaleco)||During build phase, the drums (on the noise channel) drop out fairly early.|
|Snow Bros.||When you clear the stage and rise to the next floor, incorrect CHR bank switching results in glitches in the new floor's graphics.|
|StarTropics||The island map music (NSF track 1) has a problem with the second square channel: it is intermittently silent or playing the wrong notes after the first minute or two, because the music data was not made to fit/repeat properly.|
|Super Mario Bros.||
|Super Mario Bros. 3 (U)||
|Teenage Mutant Ninja Turtles||Sprite overflow (due to large numbers of enemies) causes the status bar to flicker.|
|The Addams Family||The in-game status bar occasionally bumps vertically by 1 pixel, caused by non-solid background pixels overlapping the sprite zero that is used for the status bar split.|
|Zelda II: The Adventure of Link (U)||
Reads from $2007 during the title screen twice, moving the background upward by 2 scanlines after the split point.
Reliance on RAM values
Several games erroneously rely on RAM areas being pre-populated with certain values at power-on, despite RAM contents not being in a consistent state on power-on. Other games rely on similar values, but in PRG-RAM (WRAM), or CHR-RAM.
|Apple Town Story (FDS)||Uses RAM to determine what character name to default to when starting a new game; when RAM is pre-initialised to $00, the name キャシー (Cathy) will be used.|
|Cheetahmen II||Suspected that certain RAM values may affect being able to reach the final two levels of the game (levels 5 and 6).|
|Education Games 18-in-1 (Ch)||Memory location $5FF0 must be read as $FF, otherwise the main menu freezes.|
|F-1 Race (1984, Nintendo)||Title screen will be skipped if $6B and $70 contain non-zero values. Game blindly reads and uses values from $51, $55, $70, $A4, and $0200-02FF (via sprite DMA).|
|Final Fantasy||Relies on portions of RAM to act as an RNG seed for battles/encounters.|
|Huge Insect||Artifacts show up on the screen when nametable RAM is initialized with random values (the game only appears to initialize one of the 2 nametables).|
|Minna no Taabou no Nakayoshi Daisakusen||Requires that address $11 be initialized to the value $FF, otherwise the game will not start.|
|River City Ransom||Relies on portions of RAM to act as RNG seed for which gangs you encounter, particularly at start.|
|Super Mario Bros (bootleg versions)||Relies on portions of RAM containing $00, otherwise player starts at world 0-1.|
|Terminator 2: Judgment Day||The copyright screen is skipped if RAM is filled with $00 (more generally, if a high score table checksum happens to be valid).|
|Ultima: Exodus||Relies on PRG-RAM contents before they're initialised; a fresh/new game may see artifacts such as shaking/wobbly text during the initial text intro screens, corruption of text intro screen fonts, and possibly audio anomalies.|
|Ultimate Mortal Kombat 3 (14 People) (Unl)||Memory locations $5F74 and $5F75 must be read as $FF, otherwise the game will not start.|
"Impossible" controller input
Many games do weird and buggy things when button combinations that would be impossible (or at least very hard) to input on a real controller are pressed. This comprises pressing left+right and up+down simultaneously. You probably want to prevent impossible controller input by default in an emulator, but have an option to allow it for those feeling experimental.
- In Zelda II: The Adventure of Link, Link can gain tremendous speed when pressing left+right.
- In Tiny Toon Adventures, the player can gain unusual speed when pressing left+right.
- In Spy vs. Spy, the character turns into an airplane when pressing left+right.
- In Battletoads, pressing up+down in the vertical tunnel level kills the player instantly. Additionally, pressing left+right causes the player to walk up/back even when in pure 2D stages, which can result in certain areas becoming impossible to complete.
- In Mega Man 1, 2, by pressing up+down at the top of a ladder, one may enter the "climbing ladder" state briefly above the top of the ladder. This allows "zipping" through walls.
- In Panic Restaurant, pressing up while crouching (by pressing down, thus pressing up+down simultaneously) the player character's sprite uses garbage data including the damage sprite. This does not occur if up is pressed before down; the player chef merely stands still.
- In Teenage Mutant Ninja Turtles, If you press the attack button while you jump while pressing up+down, the player character uses a garbage sprite, and attacks will use unusual (i.e. garbage data) hitboxes.
- In Teenage Mutant Ninja Turtles II: The Arcade Game, when you jump with a left or right move while pressing up+down, the player character will move in unusual directions and speeds, possibly screen-wrapping.
Some games display junk tiles in the overscan area, which is usually not seen (or is at least partially obstructed) on real TV sets. Examples include the NTSC versions of Metal Gear (e.g. in the jungle area when gameplay starts) and Solstice (on the title screen).