Null Egg

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Individual Level Strats

World 2


World 3


World 4


World 5


World 6



  • The Null Egg was originally thought to be a random occurrence at the end of 2-2 that would cause the game to crash. That was until ArneTheGreat looked into it further and discovered that the crashes were caused by a rat carrying an egg.
  • If you grab the egg from the rat (without destroying him) and he despawns, the egg will also despawn because it is tied to the rat's sprite. When this happens, it creates an open sprite slot in your egg inventory - a null egg. This slot is subsequently filled by the next sprite that loads in, even if it's a non-egg sprite like an enemy or collectible. Since sprites being loaded into the egg inventory in this way is not supported by the game, it usually results in a crash.
  • After some experimentation, it was figured out that the boss key sprite could be obtained and then used to beat levels soon after they begin. This created the first truly broken/glitched speedrun category Magical Journey.

The following video explains how sprite ID slots work with regards to the Null Egg and also demonstrates the different uses of it.

Magical Journey
Game Crash
Null Egg Demonstration

Getting The Null Egg

The null egg speedrun categories currently get 2 null eggs in 2-2. If you're interested in the older 1 null egg route you can find videos on it near the bottom of the page.

This text tutorial corresponds to the video down on the left.

  • Enter the final screen with 6 eggs and do not use any.
  • At the top of the hill near the end, tongue the Skull Rat and then spit it into the Piranha Plant. Walk down the entire hill rather than jumping.
  • Jump and grab the egg that the rat is carrying before it falls down. When the rat despawns, you will have the null egg.
  • Go part way up the hill, turn left, scroll the screen up and then jump while the screen is scrolling up. After you jump, tongue the first rat and spit it into the second.
  • Go back down the hill, turn back to the right just long enough to despawn the rat, and then climb to the left up the hill. If you are doing Magical Journey or the 2-6 corruption in No ACE, you will want to swap 2 eggs here.
  • Walk to the right down the hill again and grab a second null egg as before.
  • Go part way up the hill again and turn left, scroll up and jump as before.
  • Continue to the right and finish the level.

Keep in mind that the game can crash upon entering the goal ring if the setup is not done properly.

Easy Setup

Getting The Boss Key Sprite

  • After getting the Null Eggs in 2-2, re-enter 1-8 to fight Salvo to get the boss key sprite into your egg inventory.
  • You want to end the fight with 2 eggs if you're running Magical Journey. These eggs will be used for upcoming levels. You can use your remaining eggs to throw at the water spitting fish in the second room, the red switch in the room after and one for the boss.
  • If you're running No ACE, see the egg routes below.
  • Right after you enter the door to the boss fight when you get hit, collect Baby Mario and bounce on the Mouser.
  • Flutter or wait for a bit until the Mouser jumps, and then tongue it.
  • In the boss fight, run a little bit to the right and spit the Mouser up into Salvo.
  • Run a little to the left so you don't get hit by the slimes, tongue one, and then jump onto a slime, so Salvo jumps with you. (Refer to the video for the exact timing.)
  • Spit the slime into Salvo. If this doesn't kill Salvo keep spitting slimes into him, being careful not to run out of slimes.
  • You will now have a Boss Explosion in your first Null Egg, and a Boss Key in the 2nd Null Egg.
Null Egg Tutorial For All Levels (Old)
1-8 Salvo Re-fight Demonstration

Save File Corruption

This trick allows you to unlock 6-8 after beating 2-6 or 3-1 by corrupting your save data. The No ACE category was created as a result to differentiate it from Magical Journey. This run is only possible on the SNES, using version J1.0

2-6 Route

2-6 Save Corruption

This route is significantly harder. Only use this route if you want to compete for top times.

  • Use file 3 for this route.
  • In 2-2, you need to collect 2 Null Eggs.
  • Grab two null eggs in 2-2 as shown above, making sure to swap eggs twice before grabbing the second null egg.
  • In 1-8, shoot the fish in the 2nd room and the platform switch, but do not shoot the pot.
  • The Boss Explosions will finish 2-3, 2-4 and 2-5 instantly. Only mash one button in the intro to 2-3 to prevent a random gusty spawn from overwriting the explosion.
  • After 2-5, the Boss Explosion will be replaced with the Seesaw Log from 2-5. This is good.
  • At the start of 2-6, run to the right, swap or shoot one egg before the keyhole opens all the way. This will delay the Boss Key enough that you can enter the door.
  • In the 2nd room, ground pound where the enemy is, wait until the keyhole starts opening up (NOT BEFORE), shoot your egg up, and make your way into the door.
  • In the 4th room, run right and make your way over the platforms. Shoot another egg to delay the Boss Key once again.
  • Once you are in the last room, flutter out of the water and bonk the wall on the right to delay running right.
  • Jump up the slope until the edge, land on the first and 2nd numbered platform, fall into the water, hold right until you are in the water, and then hold left and jump until the level finishes. (This pretty much just has a 50% chance of working, because the pixel you need to get a 6-8 save corruption is very precise)
  • Once you are back on the overworld, reset the console, and if you have done it right, you can now enter 6-8 and finish the run.

3-1 Route

3-1 Save Corruption

This route is significantly easier but loses ~40 seconds compared to the 2-6 route. It's recommended for beginners or for marathon runs, because the 3-1 Save Corruption is 100% consistent, if done right.

  • For this route you have to use File 2, instead of 3.
  • For the double Null Egg, you don't want to swap eggs. This allows us to use more eggs in 1-8.
  • Once in 1-8 again, you can shoot the fish, the switch and the pot.
  • Do the same fight as in the 2-6 route.
  • In this route, you just want to end 2-6 normally. Run to the very right, and then scroll up, to end the level faster.
  • In 2-8, you want to throw 2 eggs. The normal egg and the 1st Null Egg. Keep the last one which has the Boss Key.
  • In the 3-1 intro, only hold right and mash one button.
  • Jump up the foam, over the red coin, run up the branch.
  • Once you start falling, turn left without slowing down.
  • When you hit the wall below the 2nd branch, flutter until the level finishes.
  • Once you are back on the overworld, reset the console, and if you have done it right, you can now enter 6-8 and finish the run.

Advanced Strats

Fast Double Null Egg:

Fast Double Null Egg

For a faster version of the double Null Egg, collect both of the Null Eggs before jumping over the gap and spawning the 2 mousers.
Here it's important that you land on the very bottom of the slope and run up, and give the screen enough time to scroll up before jumping.

Fast 2-6 Room 2:

Fast 2-6 Room 2

For the 2nd room in 2-6, you don't actually have to wait for the keyhole to appear. If you want to save a few seconds, you can shoot the egg right away.
The only drawback is that you have to do the room completely blind, which is risky. Probably the easiest way of getting up the bouncy balls is by hugging the left wall and landing next to the ball and then doing a short hop onto the ball while holding right. You have to do this room fairly quickly or you will lose control of Yoshi.

Old Null Egg Route

You can also just get one null egg in 2-2 and just get the boss key from the Salvo fight. This might be slightly easier to get, but isn't worth doing in runs since it makes 2-3 thru 2-5 much slower, more difficult, and prone to randomly failing. Below are a couple videos in case you are interested in the old route.

Null Egg Tutorial For All Levels
1-8 Salvo Re-fight Demonstration
Faster Setup

Further Information

The position of the boss key sprite affects how quickly a level gets completed. Compared to having 3 eggs in front of the key:

  • Having 2 eggs loses 9 frames per level.
  • 1 egg loses 47 frames.
  • 0 eggs loses 49 frames.

The Boss Key also affects a few levels differently depending on the version. From fastest to slowest overall version it's:

  • J1.0 > J1.2 > J1.1 > U1.1 > PAL > U1.0

The Null Egg In Other Levels

3-6 Null Egg

The Null Egg can also be acquired in 3-6. A Screen Transition sprite can then replace the Null Egg to trigger a 1-1 Warp to complete the level. Unfortunately for the IL run of this level, the 1-1 Warp is slower than doing the level normally, however, the 3-6 Null Egg can be used in 100% No Restrictions to save multiple minutes.

3-6 Any% Speedrun Using The Null Egg
How The 3-6 Null Egg Can Save Time In 100%

6-4 Null Egg

The Null Egg can even acquired in 6-4! While it is harder to get than the Null Egg in 2-2, this one actually saves time in an IL run, unlike the one in 3-6, since it allows you to skip most of the room before the boss where you would normally do the Lava Skip (or take the log). A middle-ring replaces the Null Egg and upon dying and respawning, you're placed after the lava section. All you have to do after is fight Tap-Tap.

6-4 Null Egg Demonstration
6-4 Any% Speedrun Using The Null Egg

Extra Help

Head over to the DLC page to find useful tools like Lua with sprite slots and RAM watch that will help a lot to learn and better understand specific Null Egg things.