The Bad Jump Design and 30 FPS Gravity of TMNT (NES) - Behind the Code 

Very good point. I feel that hitting your head would still reduce your horizontal velocity a bit, but perhaps not as extreme as it does now. Shadow Hog! I nominate you to investigate environmental collision detection in the sidescrolling areas of TMNT!

@@DisplacedGamers Oh no! I guess I have to learn 6502 ASM now! (๑•﹏•) (FR tho, it _is_ tempting...)

While it's possible to go this route, the ultimate point of tweaking a platforming game's physics and controls isn't to arrive at "objectively easy traversal" - it's to highlight specific kinds of traversal challenges and explore the possibilities in a dialogue between level design and systems design. TMNT's head hits are a pretty clear example of designed intent. When your jumps are made easier, it's more likely that your game is making you do something else with them. For example, Metroid's jumping allows you to float and land very precisely, which frees up attention for the shooting mechanics. But Mario's jumps are faster and very tied to the horizontal running motion, and the horizontal is intentionally slidey with slow stops and starts, so Mario jumping is really about constantly feeling "out of control". TMNT is in a state where every mechanic is a muddle and doesn't know what it wants to be, but the short arcs are clearly where the platforming gameplay is supposed to feel tough and you are supposed to fail. Another way to think about TMNT's problem is: there's a disconnect between the frame of A button release and when the turtle starts falling. In a Mario-style jump you decide the top of the arc by letting go; it kills Y velocity on that frame and lets gravity take over. That makes you feel like you're controlling it precisely and it means there are a huge variety of jumps because of the combined effect of horizontal velocity and release time, which the level design uses to great effect. But TMNT wants to allow a mix of short jumps and huge screen-sized jumps from a standing start, while making it possible to do both quickly. The way in which the original design went to accommodate the different sizes was to front-load the entire control scheme so that the arc is expressed within 8 frames. That's a problem because held button inputs are never as intuitive as "on press/on release", and using three held-button states to describe the future behavior of the jump aliases the different jumps into what are essentially fighting game command specials, vs watching the character to see when they hit the top of the arc and releasing at exactly that moment. Tuning the jump as done in the video makes this input much easier, but also hurts the responsiveness of the largest jump. A literal double jump would solve this. That gives you the control, it lets you make the high jumps quickly, and it clarifies the short/medium challenge mechanic, even if we don't change the actual arcs or frame timings at all(though tuning the first jump to be a clear fall-on-release definitely makes it more appealing).

smart. i was thinking all you'd need is to assign, say, a double tap forward to a mostly horizontal vaulting jump

I think you could improve headbonking a bit by shrinking the top the hitbox a few pixels when jumping, similar to a double jump.

What is it with companies demanding ports and not handing source code over? That's four I can think of now, you guys and the 3DO DOOM people, then the disaster that was the Sonic Genesis GBA port, and the team that had to reverse engineer Nights Into Dreams for the PC port. I just watched a playthrough of the C64 version, and color me impressed! The game looks pretty much like the only things that had to be simplified was the music and graphics, it looks pretty much like the NES version I played. If you still have contact with whoever did the main theme, give them a shout out! It sounds just as rockin' as the NES version! (and the overworld theme is going to be stuck in my head again, oops)

I was playing this on a Commodore my friend has a few years ago with and was wondering why only one button was used for both up and jump (think it was up and jump it might have been attack and jump, will try it on his machine again to make sure what share it was) were you limited by source code or was it to accommodate something like the 1 button joystick controllers people had from the 2600?

I still have a C64 :) I tried programming a bit on it... Holy crap it was tedious, how did you manage with adding lines in between code?

@@radiance_37k you might be thinking of basic, where you add the line number for each line of code "10 code here. 20 code here." Then you can ask code between with "11 more code" etc. The guys who ported to c64 did so in assembly no doubt (or some kind of other low level, higher than ASM, language)

@@cradledani I honestly did not realize that was an option, nor that you could ask for more lines. Thanks for clearing that up :)

The Belmont Strut, I love it! There's also an unused subweapon that functions similar to holy water from CV that was found. Possibly related to one of the initial subweapons pitched being a bomb item that does area damage.

Most likely, given Ultra was simply a sub-company of Konami, to bend the games per year released limit imposed by Nintendo

Possibly why the input lag for attack was programmed into the game... To have that Castlevania feel. It's an action game but in a different pace

You mean Belmont uses the Turtles walk right? Lol.

It very much IS a classic, just in that butthead-difficult kind of way that Battletoads and Spelunker are

@@TonyTheTGR Nintendo Hard classics, ah, how I (don't) miss thee.

Ar

Kaizo TMNT 😈

Another big problem is there's no invulnerability time after taking damage.

Yeesssss! That is a great strat.

This.

The NES Max was really good for that since the big downside of the NES Advantage was that you had to toggle the turbo mode on and off for your buttons, whereas the Max had dedicated turbo buttons. Only downside of the Max was that darn sliding D pad.

Personnally, my strat for those jumps was to simply quick-tap the button and barely touch it...

@@-Keith- I had the max growing up. The dedicated turbo buttons were invaluable. To get around the dpad problem, just got used to pressing the black frame around it.

Yeah... I suppose it was a natural holdover as gaming evolved over the years. Processors got faster, but tying physics to the frame rate still saved time.

Anyone that plays Elder Scrolls game should get chills as well.

@@themonsterunderyourbed9408 I didn't get chills, I deadbutt _flinched_ .

@@neoqwerty dead ass

When Ben Heck did it on his game on a microcontroller, I left a cheeky comment about how he was tying the game's physics to frame rate, but in reality, this kinda used to be the only way to do it in time. I suspect anyone who saw my comment knew that as well.

It's not a double jump, just a high jump. A double jump is like in Castlevania SOTN where you can jump again when you are in air.

@@JohnSmith-nj4zq But in the video it's considered an automatic double jump, which in my opininon is an accurate description since the game gives you a new starting velocity mid-jump, like you'd get out of a more common double jump.

@@JanneSiimesvaara It's more like Street Fighter 2, There's a low, medium and high. SOTN jumping twice is what an actual double jump is and looks like.

Thank you, and thank you for the share!

He fixed the water level in his previous video.

Mario did it by just holding the upward velocity constant until the jump button is released or a frame limit is reached. After that you're released to gravity.

​@@khatharrmalkavian3306from what I understand, at least in Super Mario World, the game still keeps checking if the jump button is held while in the air regardless of time This leads to the phenomenon that speedrunners coined "regrabbing" where you hold the jump button again at different descending points if your jump for some extra horizontal distance. It's funny how such little changes to code can basically add a high skill mechanic like that lol

Thanks again for all your hard work! Love your stuff!

Quality of life rom patches are life!

@@SirBuzz yea it is. Games are released with busted code cause they ran out of time and this is as good as it gets. Have you seen the smb64 code fixes??? The dumbasses left debugging on and just turning it off bumped the performance like 20%. Debugging was left on. That’s not part of the gaming experience.

I haven't played on an emulator in a long time, but my suggestion is to play with turbo fire if you have the option. On the NES, if you use the NES Advantage, turn on the Turbo and set it to max. You'll get a short jump 100% of the time. That's what I did when I was a kid and it made the jump at 9:05 elementary.

I think TMNT nes game was designed for the 30 fps jump if you play the game some jumps really feel like it the jump he shows in the video couldn’t be made at a 60 fps jump

It's a good idea, but then it should be rebranded as a new version not to be confused with the original.

Is almost like they are tortoises, not turtles

Strong currents

@@affegpus4195 Tortoises are turtles.

@@ciceronx Tortoises are land animals and can in fact not swim.

Not to mention it's got some equally impressive, sophisticated gravity physics going on by NES standards. Which just happens to be pretty relevant to this vid. 😁

Yeah, you see some ingenious workarounds in some of the old coding, true masters of their class at the time.

It was made by Rare if I'm not mistaken, so it's likely CHR RAM based utilizing a lot of tile compression among other things. They had a habit of really trying to push the hardware.

Solar Jetman levels are made from 256 different 128*128 pixels big metatiles. This substantially reduces the size needed to store all levels. Planet 2 for example is 32*26 metatiles big i.e. only 832 bytes is needed for the level's layout. They did a really good job with the levels so these big blocks aren't really noticeable.

Solar Jetman example image where the metatiles are outlined and their ID/number (0-255) shown. drive.google.com/file/d/1UBtwvcrjnp2ccuXgDld97YBxaHPUmris/view?usp=sharing

While I wish we didn't live in a "release now, patch later" world, it sure is nice for devs to not only fix bugs but also tweak mechanics after a game has been released. Pairing this approach with a physical release that does not contain those patches as well as the possibility that the server that provides those patches could no longer exist at some point in the future is a cause for alarm for those that may want to revisit a PS5 game (for example) 20 years later.

back then they did not have the tools and what kind of cuts / quick changes where made to make the games fit into the rom space / cpu power / ram? Other stuff cut for time leading to quick changes to get the game out on time?

Thank you. I really appreciate it!

Thank you so much, John!

You can actually manipulate the current and ride it as long as you dont bonk against any walls. We usually try to stay in a current during speeruns.

@@retrogambit7101 - You're a runner? Me, too! A humble 23:13 in Any%, but that may improve if I can learn the secrets of boost/current. Sometimes I'll be bonk-free and still miss current, so I'm trying to figure out what I'm doing wrong, or what knowledge I'm missing.

@@rawkfistgaming Skunky has a great tutorial on current boost. Not sure if its on SR or his YT

@@rawkfistgaming Im also trying to improve my Glitchless run and Any%

@@retrogambit7101 Oh, he does??? NICE! I initially learned off one of his runs, but recently I started using Stuff is Stuff's tuto. Gonna have to go give Skunky some more views, lol... Thanks, man!

I remember that jump being impossible on the PC version. Until I discovered the can't-die cheat code to just walk on water

I could never make that jump. No matter how many times I tried, I never once made it.

I would love a full 60 fps conversion

Thank you!

While I haven't looked at Mega Man 2's exact jump mechanics, I believe it has what you are describing. I showed some footage from it in this video. If you were to duplicate the jump logic from Mega Man 2 for TMNT, you'd have to consider adapting for 30 fps and probably adding the automatic double jump to the end for jump height requirements. Platforming in the NES Mega Man series feels good, and the frame rate allows for it.

Yeah I didn't expect it either and never noticed it when playing. I can't think of a good alternative since the game has no run button and no specific double jump button to make it explicit.

Thank you, James. Your comment means a lot as I want the video to be as accessible as possible despite loading it down with technical information.

Thank you!

What would you like to see in the Mega Man series?

Anything, really. I enjoyed the videos on zipping and QuickMan's AI. Perhaps a glance at how the code evolved for how MegaMan moves around from 1-6? Might turn into a lengthy video, though.

But... they CAN swim. There's an entire level dedicated to it.

@@Pulmonox They forgot this logic gap when you fall in water in a sewer.

@@Raytheman581 It's clearly _holographic_ water, planted there by Shredder to trick them into falling to their death in a black hole!!!

@@neoqwerty Darn that Shredhead! What will he think of next.

I assume they still have access to the original source code and didn't lean on the wrapper-emulator alone for all of their tweaks, but maybe that was the extent of their changes. That said - I am not sure if the ROI for putting time into tweaking the original game mechanics is worth it for them.

Go for it! You'll probably make the tweaks even better!

Wouldn't be surprised if that's the case: Mega Man games in particular, I recall, where often made on a death march-pace and I wonder if even this game, big a license as it was, was made with enough time to really work out CPU-freeing solutions or if it was just "do whatever to get it working it needs to be done now now NOW!" With our increased knowledge, documentation and time, so much more is possible now than was back then...

PureSabe is _nuts_ with what he squeezed out of MM4... And he did it again with Rockman 7 EP!