Tricky-to-emulate games

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This is a list of various emulation bugs encountered during the development of Mesen-S. It is meant as a quick reference to help others find and debug issues with their own emulation core. It can also be used to find games that might be affected by a code change, for regression testing purposes.

Cause Affected games
Missing/incorrect open bus implementation (CPU or PPU)
  • Captain America and the Avengers: Broken graphics during gameplay
  • Combatribes, The: Doesn't boot
  • Home Alone: Crashes after main menu
  • Rock n' Roll Racing: Broken graphics in character select
  • Super 3D Noah's Ark: Broken mode 7 graphics
Incorrect or missing BRK/COP implementation
  • Actraiser: Crashes after menu
  • Bishoujo Senshi Sailor Moon - Another Story: Crashes after menu
  • Cybernator: Intro restarts when starting game
  • Dekitate High School: Doesn't boot
  • Illusion of Gaia: Doesn't boot
  • Kamaitachi no Yoru: Doesn't boot
  • Soul Blazer: Doesn't boot
Incorrect ORA [d] implementation
  • Super Mario World: Corrupted overworld map (bad 3bpp decompression)
VRAM writes are not ignored during rendering
  • Hook: Text glitches during intro
Ignored VRAM writes during rendering are not incrementing the VRAM address
  • Kick Off
VRAM read implementation is incorrect
  • Breath of Fire
Offset-per-tile wraparound logic is incorrect
  • Super Famista 5: Issues at the top of the screen during animation inside the main menu
Offset-per-tile implementation has bugs
  • Axelay: Broken level background in some areas of stage 2
  • Chrono Trigger: Broken layout in in-game menu
Mode 7 doesn't implement window logic
  • Atlas, The - Renaissance Voyager: Broken mode 7 graphics during intro
  • MechWarrior: Broken mode 7 graphics during gameplay
Mode 7 scroll offsets are not latched at the beginning of the scanline
  • NHL '94: Glitch scanline in the middle of screen during intro animation
Mode 7 direct color implementation is wrong
  • Aerobiz: Wrong colors during intro sequence
Color window is not applied to all pixels
  • Krusty's Super Fun House: Broken graphics at the edges of the screen
Color math for subscreen in high resolution modes is incorrect
  • Jurassic Park: Broken graphics during gameplay
Implementation of OAM writes during rendering is inaccurate
  • Uniracers: In 2-player mode, second player's unicycle doesn't display correctly
OAM fetching/rendering timing inaccurate
  • Mega lo Mania - Jikuu Daisenryaku: A single black line appears in the middle of the screen during the intro
DMA controller power on state is invalid
  • Heian Fuuunden: Corrupt title screen when pressing start to skip opening animation
CPU doesn't run an extra cycle before starting DMA after write to $420B
  • Mighty Morphin Power Rangers - The Fighting Edition
DMA controller allows reading B-bus registers using A-bus address
  • Krusty's Super Fun House: Wrong colors during gameplay
DMA/HDMA timings are inaccurate
  • Circuit USA: Broken graphics in menu
  • Jumbo Ozaki no Hole in One: Broken graphics in menu
DMA is not suspended when HDMA runs
  • Dekitate High School
HDMA doesn't ignore "fixed transfer" flag
  • Batman Forever: Broken mode 7 graphics during intro
  • Lost Vikings, The: Black screen when gameplay starts
HDMA doesn't ignore "decrement" flag
  • Adventures of Kid Kleets, The: Broken graphics at power on
  • MechWarrior: Broken mode 7 graphics during gameplay
HDMA ignores "direction" flag
  • Pocky & Rocky: Broken license/logo screens on power on
HDMA "do tranfer" flag isn't set/reset properly
  • Aladdin: Broken graphics in the background on first level
  • Super Ghouls'n Ghosts: Black screen once gameplay starts
V-IRQ doesn't trigger when V-IRQs are enabled for the current scanline
  • RoboCop versus The Terminator
NMI isn't triggered when NMI is enabled partway through vertical blank
  • Alien vs Predator: Screen flashes during gameplay
  • Pocky & Rocky: Screen flashes during gameplay
When NMI is triggered as per above, CPU jumps to interrupt vector immediately (should run 1 more instruction)
  • Jaki Crush: Doesn't boot (may depend on other timing)
SPC timings are inaccurate (requires SPC to run 1 cycle at a time, rather than 1 instruction at a time)
  • ActRaiser 2: Freezes
  • Hiouden - Mamono-tachi to no Chikai: Broken sound
  • Illusion of Gaia: Doesn't boot
  • Tales of Phantasia: Missing sound effects, freezes
CPU read effects do not occur early enough in the CPU's cycle
  • Rendering Ranger R2: Freezes due to infinite loop with SPC
DSP KOF register is not initialized to $00
  • Chester Cheetah - Too Cool to Fool: Missing sound effects
  • King of Dragons: Missing sound effects
SRAM mappings are incorrect
  • Fire Emblem - Thracia 776
  • Ys III - Wanderers from Ys
RAM power on state is "incorrect"
  • Bishoujo Senshi Sailor Moon - Another Story: Random static in music during intro (when SPC RAM is randomized)
  • Death Brade: Duel ends instantly when RAM is initialized with 0s
  • Power Drive: Broken graphics when RAM is initialized with 0s
  • Super Keiba 2: Blackscreen after a few menus when SRAM is initialized with 0s
Super FX - RPIX implementation is incorrect
  • Yoshi's Island: Broken effects in tunnels[1]
OAMADD priority sprite rotation is missing
  • Super Mario World: The lives-indicator Mario is hidden at the top left of the map screen
HDMA can't affect open bus
  • Speedy Gonzales: Los Gatos Bandidos: Game locks up in level 6-1[2]

See Also