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Proto:Super Mario Kart/kart_*

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This is a sub-page of Proto:Super Mario Kart.

This article is a work in progress.
...Well, all the articles here are, in a way. But this one moreso, and the article may contain incomplete information and editor's notes.
To do:
  • Check for unused data in the rom.
  • More screenshots.
  • Finish track differences.

A later build than April 13 build, and very similar to the unreleased prototype, though it still has some differences. The ROM has a timestamp of May 18, 1992, and is in English, unlike the earlier April 13 build.

The build is actually split into two files: kart_01, which is the base ROM, containing the game's main code and assets, and kart_02, which contains data related to the debug menus. To get the build working, append kart_02 to the end of kart_01 and then apply this patch.


SMKMayAugustProto RR.png
Early Tracks
Rainbow Road without Thwomps?
Early Audio

Changes between this and earlier build


  • The small demos seen while sitting on the title screen are now added in (but unfinished).
  • The fourth place ending is now implemented.
  • The tracks are now in their final order.
  • The unique 2nd and 3rd place ending cutscenes have been swapped around, and have small changes in the animation.


  • Battle Course 4 (Battle Course 1 in this build) now takes place in Mario Circuit.
  • Computer opponents now use character specific items. They now throw items ahead too.
  • The player can now hop with L and R.
  • Choco Island 3 has now been replaced by Rainbow Road.
  • In Battle Mode, the players now start in the center of the map facing each other.

Graphics / UI

  • Luigi now uses Mario's body graphics, though he's still looking straight ahead rather than up.
  • After losing a race, the red "RANKED OUT" tagline is now added and now brings up the "Retry" and "End" options. Previously, it would bring up the lap times and load the results screen before restarting the race.
  • It now displays the Round number when a race starts.
  • There is no longer a timer in Battle Mode.
  • Results/Standings screens now have their final layout, and the tallying is now animated.


  • Coin SFX is now final.
  • Title screen uses its proper theme.
  • Mario Circuit, Choco Island, Ghost Valley, Bowser's Castle, and Battle Mode now have their proper themes.
  • The No Record jingle has been finalized, but is still used as the 2nd-4th jingle.
  • The Game Over jingle has been added.
  • Donut Plains BGM is now in its final key.
  • The players engine noise can now be heard during the countdown, but due to the absence of the rocket start/burn out, there is a cap in the pitch for the engine noise when holding down the button.
  • Character taunts for passing other racers are now added.
  • Peach and Yoshi now use their final engine sample.

General Differences

  • The logo is still based on the Japanese version. The background already got updated to the international version, by removing the Japanese text.
  • The demo sequences appear to be desynchronized, which results into drivers driving into walls.
    • The proto has a total of 8 demo sequences with different scenarios, while the final only has 4. Demos 6 and 8 make use of the secret screen swap trick and the map tiles are corrupted in demos 4, 5, and 8.
Proto Final
Demo Sequence Player 1 Player 2 Demo Sequence Player 1 Player 2
Demo 1

(2P GP, Mario Circuit 1)

Mario Peach Demo 1

(2P GP, Mario Circuit 1)

Mario Yoshi
Demo 2

(1P GP, Ghost Valley 1)

Yoshi N/A Demo 2

(Time Trial, Donut Plains 1)

Donkey Kong Jr. N/A
Demo 3

(Battle Mode, Battle Course 1)

Koopa Troopa Toad Demo 3

(Battle Mode, Battle Course 4)

Koopa Troopa Toad
Demo 4

(Match Race, Bowser's Castle 2)

Bowser Luigi Demo 4

(1P GP, Choco Island 1)

Peach N/A
Demo 5

(Time Trial, Donut Plains 1)

Donkey Kong Jr. N/A N/A N/A N/A
Demo 6

(1P GP, Ghost Valley 1)

N/A Peach N/A N/A N/A
Demo 7

(Match Race, Mario Circuit 1)

Luigi Mario N/A N/A N/A
Demo 8

(Time Trial, Bowser's Castle 2)

N/A Bowser N/A N/A N/A
  • You cannot navigate the menus using Select, unlike the final version.
  • The cup selection screen lacks an orange border as well as showing which CC you've chosen.
  • Everything is locked from the start, unlike the earlier prototype.
  • Course Select is misspelt as Course Selct in the course selection screen.
  • Time Trial ghosts are not implemented yet
  • The replay system in Time Trial is not implemented yet.
  • During the result/score tally screen, the CPU that don't manage to finish in time get an "OUT" instead of their time like the final.
  • The coin UI does not flash yet when having 0 coins. You still spin out when touching racers while having 0 coins, however.
  • Before receiving your first item the item roulette space shows 1p and 2p, which was changed to just 1 and 2 in the final.
  • The drivers (with the exception of Mario, Yoshi, and Toad) are arranged differently on the Driver Selection screen, and is the same order as the earlier April build.

Gameplay Differences

  • You start with 4 coins instead of 5 in the final.
  • You start out with 2 lives instead of 3 in the final.
  • The driver stats are still slightly different.
  • Starting boost or motor burn at countdown is completely missing.
  • Falling into the lava, water, or of the map doesn't give a coin penalty. Oddly enough this is present in the earlier prototype from April 13, 1992.
  • Monty Moles do not attach on you; instead, you just spin out.
  • Cheep-Cheeps and Piranha Plants will cause you to lose coins when you touch them.
  • You can still lose coins after you've finished and bonk into someone.
  • Drifting in circles does not eventually spin you out. This worked fine in the earlier April 13, 1992 proto. This was perhaps due to the drift mechanic being changed.
  • You do not get an extra life after you've finished first three times.
  • The CPU appears to not be able to get hit by dropped bananas, as well as items fired by other CPU's. As a result, you never see other CPU players getting hit on the minimap way behind you while playing, unlike the final.
  • The CPU doesn't attempt to avoid you yet, creating situations sometimes where they bonk endlessly into you. This is especially common when a character with a lighter weight than yours rams into you from behind.
  • Special Cup is now locked by default in Time Trial, but the button code to unlock it hasn't been implemented yet.
  • The mud in Choco Island and the wet dirt in Donut Plains is more slippery when driving on it.
  • The Thwomps always move during the 1st lap. In the final, They start moving in the second lap.
  • Cheep Cheeps now have another unique behavior when shot by Koopa shells. They will fly away a little and play an "item destroy" sound.
  • Toad and Koopa Troopa lack the ability to carve (Inwards drifting mechanic performed by tapping L/R as opposed to holding L/R normally) in courses like Mario Circuit, Ghost Valley and Bowser's Castle. Their skidding is the same as the other characters.
  • The small boost (similar to a mini-turbo) received from releasing a drift is absent.
  • It is still possible to skip the win sequence by pressing start after finishing a race.
  • During the demo sequences, it's possible to alter the racer's steering directions by pressing/holding L or R to make them skid.
  • The CPU appears to go slightly faster and they tend to attack with items more excessively. This is most prevalent when playing as a slower character, like Toad or Koopa Troopa.

Bugs / Issues

  • Rainbow Road has the graphics missing for the position counter, thus crashes when the final lap is reached, making it incompletable. This makes completing 100cc impossible without applying this patch by MrL314.
  • In Battle Mode, going out of bounds using a feather causes you to become permanently stuck, similar to the undumped prototype. Lakitu will carry the player far away from the map, and will eventually place down and pick up the player in an endless loop. This is due to the checkpoint targets in all the battle tracks pointing to an area far out of bounds from the lower right portion of the map. Oddly enough this works completely fine in the earlier prototype from April 13, 1992.

SMK MayProto BattleModeGlitch.png

  • When Lakitu pulls you over the finish line, the lap won't count.
  • Lakitu still doesn't turn you in the right direction sometimes when picked up.
  • When racers finish before you do, they often don't cheer or have their position flashing, due to unknown reasons. This once again works fine in the earlier April 13, 1992 build, however, where it flashes normally until position 4 at all times, like the final.
  • The player will slow to a crawl after finishing the race in Time Trials.
  • Finishing a race while hopping makes you float in the air.
  • In Battle Mode, the loser can still drive around after the battle is over.
  • The player can cause a bug where the flashing tire palette (Emulates the tire roll when you throttle) on Luigi's kart will continue to flash even when he remains idle. This is exploited by quitting or finishing a race while at full speed.

SMK MayProto LuigiGlitch.gif

  • Sometimes the map tiles will be corrupt when the track is loaded.

SMK MayProto TileGlitch.png

  • Using a lightning as soon as you finish the race will cause the strobe effect to loop.
  • Like the earlier April build, Koopa Beach 2's checkpoint data hasn't been updated for the AI to take the shallow water section, so they run into the wall and sink into the water.

Item Differences

  • Lightning does not really cause the AI to slow down.
  • Using Lightning doesn't cause the racers to spin out when used.
  • Characters made small by Lightning or a Poison Shroom cannot be squished.
  • Touching bananas put you on full stop like green shells.
  • Going over an obstacle like pipes and Piranha Plants with a star make you feather jump instead of destroying it.
  • Bananas can't be thrown forward and shells can't be dropped.
  • Being invisible from using a Boo does not protect you from item attacks nor can you pass through other racers.
  • It's possible to get Stars and Lightnings in 1st place due to to the unpolished item distribution.

Debug Mode & Commands

An extensive Debug Menu can be accessed on the titlescreen by pressing Start + Select. Accessing it will also enable Debug Mode in a race/battle that features numerous input commands and debug features such as a RAM viewer and item debugger. The Debug Menu itself inlcudes various tools like course editor tools and sound tests. Due to Debug Mode being made for the Japanese version of the game, some menu options on the main menu have corrupted Japanese characters, because the Japanese tileset been removed from this build. Furthermore, upon activating the main debug menu (Start + Select) starting any course will load course configurations such as AI checkpoints and objects from SRAM instead of the Rom itself (which can crash the game when not configured properly).

More information about Debug Menu here:

Debug screen.png
Super Mario Kart Debugging Menu
Description of the Debug Menu in Super Mario Kart's Prototypes

Title Screen Debug Commands

The earlier April 13 build has much more title screen commands compared to this build.

  • Start + Select: Enter main debug mode
  • Select + B: Start a 50cc Mushroom Cup race
  • L + A: Changes the first unknown value on the title screen with Debug Mode activated. Goes until E. For some reason increases by 2 values with each press.
  • L + X: Changes the second value on the title screen with Debug Mode activated. Goes until 3, and sets the World (Cup) value.
  • L + Y: Changes the third unknown value on the title screen with Debug Mode activated. Goes until 8. (Might be for driver selection, but doesn't work?)

Soft Reset

Start + Select + B + Y: Soft reset back to the title screen (can be used everywhere).

Battle Mode

The Battle Mode track order is the same as the April 13 build, with the presence of a Choco Island themed Battle Course 3, which would later be supplanted by the final game's Donut Plains themed Battle Course 1.

Course Name (Prototype) Name (Final)
Donut Plains N/A Battle Course 1
Koopa Beach Battle Course 4 Battle Course 2
Choco Island Battle Course 3 N/A
Vanilla Lake Battle Course 2 Battle Course 3
Mario Circuit Battle Course 1 Battle Course 4

Award Ceremony

Like the earlier April 13 proto, there are several unique endings for ranking in the top 3 with two of them getting removed in the final.

Some changes were made. The unique 2nd and 3rd place ending cutscenes have been swapped around and have small changes in the animation.

1st 2nd 3rd
SMKmayproto Award1st.gif
SMKmayproto Award2nd.gif
SMKmayproto Award3rd.gif
  • In the 2nd place ending, the Super Koopa now spins after getting hit by the cork.
  • In the 3rd place ending, The fourth Paratroopa bounces its way out after getting hit by the cork.

Other Notable Differences

  • The text formatting differs slightly. "GOLD.", "SILVER.", and "BRONZE." is on the same line as "GREAT RACE!". In the final, They are on the same line as "X WINS THE".
  • In the 4th place ending, the top 3 rankers continue to cheer. In the final, they don't.
  • On rare occasions, the cutscene may load with the incorrect palette, similar to the undumped prototype.
  • There is a unique sound for when the giant Cheep-Cheep balloon gets hit by the cork and flies away.
  • The sound for when the "CONGRATULATIONS" text bounces after the zoom-in is missing.