Alex Kidd in Shinobi World is a platformer for the Sega Master System. It is the final entry in the Alex Kidd series and it is a parody of Shinobi, a ninja themed action game also by Sega. Alex Kidd must save his girlfriend who has been kidnapped from planet Shinobi. Many interesting features are added to the series such as wall jumping, the ability to turn into a fireball after swinging on a bar or post and zipping from ladders and tornados by holding U+D/L+R. This TAS is a 2817 frame improvement to the published movie.
Tricks and Techniques
Alex’s speed when in a fireball is 0x0300 which is higher than normal walking speed 0x0180. Once this fireball phase ends pressing right will make him snap back to the normal walking speed. Not pressing right makes him slow down by 8 velocity units per frame. So letting go of right until 0x0180 speed is reached again saved time. Sometimes jumping can be used to extend this period by a frame or two. This is also applicable when leaving downward slopes and is used in the published TAS.
It is possible to zip on ladders by holding up and down or left and right or some combinations of buttons involving U+D or L+R. Depending on which combination is used, Alex gets shot in a certain direction sometimes up to 60x walking speed. Usually U+L+R is useful since it sends you up rather than down. While this was used in the published TAS it is extended here and is the source for most of the time saved. This TAS adds a zip across a screen without a ladder by zipping across a screen transition. Also, this TAS introduces a similar zip using the tornado powerup. Many of these major improvements have been found within the RTA community.
A minor new trick is wall jumping to gain speed. When falling through a tight gap then moving left or right it can take a long time to build up speed. But if you wall jump the speed is nearly instant. The only places I found to use this were in 3-2
Useful RAM Addresses
| X | 0x020D |
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| X (Sub) | 0x020C |
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| Y (Big) | 0x0212 |
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| Y | 0x020B |
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| Y (sub) | 0x020A |
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| Screen X | 0x0051 |
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| Screen X (Sub) | 0x0050 |
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| Screen Y | 0x0063 |
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| Screen Y (Sub) | 0x0062 |
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| X Velocity | 0x0211 |
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| X Velocity (Sub) | 0x0210 |
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| Y Velocity | 0x020F |
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| Y Velocity (Sub) | 0x020E |
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| Boss Timer | 0x031D |
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| Recovery | 0x0228 |
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| Tornado Timer | 0x0220 |
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| HP | 0x022E |
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1-1 (-2 frames)
For some reason killing the enemy at the start actually saves time. I was able to save 2 frames on the jump up the second pole.
1-2A (-570)
This level consists of an upwards section followed by a horizontal section. The zip upwards was used in the previous TAS but the horizontal zip is new. I managed to save some time on the upwards zip. Getting the horizontal zip is very strange. Originally my method was to glitch the graphics on the horizontal screen so that there was a ladder there that I could use to zip after the screen transition but I found a faster method which lets you keep the speed across the transition.
In testing I was able to skip the transition completely but I wasn’t able to replicate it after many hours trying even though I knew the exact position that I did it. It’s probably the case that I unknowingly loaded a savestate after the screen scrolled which would have produced that result.
Interestingly there seems to be a portion of 1-1 underneath this level which can be accessed by zipping. It remains fairly in tact and even has a properly loaded tileset!
1-2B (-34)
I was able to save 10 frames at the start of this room due to my remaining invincibility frames from the previous screen. The previous TAS didn’t have this luxury as it took the damage much earlier on the previous screen. I save the other 24 frames from optimization of breaking the blocks and moving around the walls while falling instead of bonking them.
1-3 (Boss)
This boss looks simple, but optimizing it was quite difficult since it’s hard to avoid his bounces while still hitting him as fast as possible.
2-1 (-2)
There wasn’t much to this level. I managed to save 2 frames from what I think was entering the door. Inside, I needed to kill the enemy to avoid hitting it during the zip.
2-2 (-4)
I saved a frame on the second damage boost and a frame entering the door. Another 2 frames were saved inside the room. I don’t know exactly how, but my theory is I managed to take a small amount of speed through the door.
2-3 (Boss) (-16)
This was the hardest level to TAS without a doubt. At this level the previous TAS desyncs on Bizhawk 1.11.9. The helicopters are completely random. My strategy for optimizing it was to get as many helicopters to spawn as quickly as possible, then worry about which way they fly. There can be 8 helicopters on the screen at once and you have to kill 14 to beat the boss. While I was fairly happy with my RNG manipulation, I could never be completely satisfied with this boss.
3-1 (-1656)
Here is the first instance of tornado zipping. I do a jump before touching the tornado power to get some more height. I couldn’t figure out a way to zip that avoided a small section of upwards zipless movement so I take that section at the top of the screen. It’s extremely easy to break the map by zipping and cause the loading zone to become inactive. Even worse, sometimes the loading zone ends up with a strange property where it sends you infinitely up resulting in a softlock. There Is a glitchy portion of 2-1 underneath the vertical scrolling part of this level.
The horizontal scrolling made a lot more sense than the vertical scrolling. The strategy here is to hold ULR to send Alex way above the level, then start holding DLR to get very fast right and slightly downward movement. These need to be balanced since if you are too high you have to wait for Alex to fall down and if you go too low you die.
3-2A (-12)
I was able to save 10 frames near the end of the level, just before the rope by performing a wall jump. This makes Alex turn around much faster than normal. I saved 2 more frames on the ending of the screen.
3-2C (-32)
I saved a lot of time overall on this screen but it was scattered across many small places. The main technique that saved time was wall jumping to get up to full speed faster after falling down a narrow gap. I also saved some time with velocity management in the cases where I had to slow down.
3-3 (Boss)
There’s not much to this fight, but the first time I did it I lost 2 frames. I don’t know why that was but I redid it and got them back.
4-1A (-16)
I found some useful techniques with the slopes. When going up a slope there seems to be a very specific spot you can land on where you can jump off again and lose no speed. When starting to go down a slope your speed drops from the standard 180 to 100 before going up to the speed of 200 for going down a slope. This is a speed cap so by letting go of right Alex slows down to 178 for the 2-4 frames that would usually be 100. Using these techniques I saved 2 frames on the first downhill slope, 2 on the second, 2 on the uphill slope after the chest, 3 after the spikes, 6 on the last slope and 1 frame entering the door.
4-1C (-419)
Here the tornado glitch saves a lot of time. The same strategy as the horizontal section of 3-1 is used. Interestingly, if you hit the bottom of the screen towards the end of the level the game freezes. This is most likely because the pitfalls in the level send you to a map below in the same spot but the right side of the upper screen is past the right boundary of the lower screen.
4-2 (-44)
The previous TAS gets health in the first room. I don’t need the health since I zipped across 4-1C and didn’t need to damage boost there. This saves 42 frames. Somehow I also saved 2 frames in the Kabuto refight.
4-3 (Final Boss) (-10)
I use a different strategy for this fight. Instead of putting the boss against the wall in the second phase I just do it as fast as possible without relying on the wall. This means I lose 4 frames in the second phase. However, I end up closer to the boss in the third phase which gets 14 frames back.
Thanks
RobynS: For creating the published TAS which was a great basis for this one.
Btrim: For suggesting this as a TAS game and making me aware of the possible improvements
KrazyRasmus: For finding the original horizontal zip across 1-2 and giving advice for recreating it.
Masterjun: Great improvements with crazy zipping! I also liked the commentary video. Accepting to Moons as an improvement to the
previous run.
