Has there ever been a trick to that notorious Sonic 3 cheat?

Just to continue on that (hopefully not off topic to the main topic)...

At the end of Carnival Night, you get shot out of a cannon in a direction of the sky, to end up in Flying Battery. Jumping down from the ship can translate easily to Ice Cap. I never thought about the door being used as the snowboard though.
Knuckles path uses some kind of a teleporter, and if it is there in Sonic 3 (placed as an object, or part of the level design,...... wait I have to check that... That's interesting!

EDIT:
The Knuckles teleporter is part of the level design of CNZ Act 2, but in ICZ Act 1, there is no teleporter at all in the area where it is located in S3&K.

Also checked Knuckles LBZ Act 1's middle boss to see if it would activate, but it didn't. This is weird because I have memories of it activating back in 1995 when I only knew Sonic 3's debug mode. I remember having two bosses fallowing me. I debugged LBZ more than any other level back in those days. Did I have a unique Sonic 3, or a bad memory mixed with S3&K?

 

Yeah, the transition from Carnival Night Zone to Flying Battery Zone is something that I had in mind for sometime now, but I never thought about the door being used as the snowboard as well.

And, about Launch Base Zone, I must say that I am in the same boat as you, because I too remember to activate the boss as Sonic, and having two of them following me, and I must say that I debugged LBZ to death. Weird.

 

I always found that I'd succeed more often if I turned the pad on its side so I was actually pressing in "right, right, left, left, right, right, right, right.

Never pulled it off on an emu though.

 

I just did the cartridge swap method the other day on my Genesis, and it worked the second time. I never did realize how many errors occur with Debug Mode in Sonic 3 alone. (I'm mainly talking about the "wrong level" part of it, when the game tries to load the previous level you were in while you performed the in-game reset cheat and you pick a different level...)

 

That's because point markers remember which act you're on. You're not supposed to be able to leave a stage without entering a Bonus Stage apart from clearing the stage or getting a game over, in either which case the current stage IS cleared. Nonetheless, this was fixed in Sonic & Knuckles. If you exit to the title screen, the current stage is cleared, so the bug never occurs.

You can do cool stuff with it, like resize the boundaries and disable the water of Angel Island 2, allowing you to play through Knuckles' stage normally.

 

Thanks for reminding me about the screen limits. I started up Marble Garden Act 1, placed a starpost, and then restarted into Angel Island Act 2. Then went into knuckles Mid Boss area, and the water and screen limit changed to allow Knuckles path to be played. This is really nice since there is no knuckles in Sonic 3, but the most of the levels are done for knuckles. They must have had some playable Knuckles code, but removed it for Sonic 3, because all the paths have the properties of Knuckles, such as jump height, forced climbing, and special breakable walls just for Knuckles, all proven in Marble Garden, Carnival Night, Ice Cap, and Launch Base. However for Angel Island, Sonic can play through the whole act 2 without any issues. Very narrow ceiling though!
Best part (idea) of Sonic 3 by far, is the dividable paths for Sonic & Knuckles!

 

What confuses me is that the separate paths for Sonic and Knuckles are far more distinct and pronounced in the Sonic 3 zones than they are in the SK zones. The whole of AIZ2, the end of MGZ2, pretty much the whole of CNZ, most of ICZ2, and pretty much the whole of LBZ2 are completely different between Sonic and Knuckles, yet only the start of each act of MHZ, a small detour through SZ2, and the most of LRZ are different (HPZ and SSZ are too short to count).

It's almost as if they designed Sonic 3 for separate characters, and then forgot about them in Sonic & Knuckles.

 

You can get into Knuckles' AIZ2 without playing starpost tricks - if you just go through normally with debug on, and then debug through his breakable wall, the screen resize and water drop will work fine (or use PAR code FFB038:02 to break down the wall as if you were Knuckles - this will lead to some glitched up sprites in a few places, which look like they may be a result of using some of Knuckles' mappings). The only caveat is that you have to still be in "act 1" - if you started from act 2 or already beat the boss, it won't work. Makes me wonder why they made it more character-dependent for S3K.

And although the boss won't appear in Knuckles' area, you can use PAR code FFFA81:01 to make Sonic's AIZ1 boss in Sonic 3 alone shoot bombs like Knuckles', so they obviously already had harder bosses planned too. (This code also affects HCZ2 and, most interestingly, LBZ2).

And I'd forgotten, but the trick of entering the code as UUDDUUUUUU... is exactly what I used to do to get the code working consistently (combined with a sideways d-pad). It's nice to finally know why that worked and why it seemed to trigger on a different number of "up" presses on different occasions.

Going from memory here, but I've got a feeling that's actually the same in S3K if you go in there with another character - I think it's spawned as part of Knuckles' intro.

 

Keep in mind that Flying Battery was supposed to come after Carnival Night Zone, which might account for why it's not designed with any radically different paths for Knuckles.

 

I thought the reason Flying Battery wasn't included in Sonic 3 was because it wasn't finished?

 

Not being finished and not being planned out aren't the same thing. Clearly it was far enough along to at least appear in the level select menu. In fact, ALL of the S&K levels that lack significant Knuckles-only alternate pathways appeared in the level select menu: Flying Battery, Mushroom Valley, and Sandopolis. The others are mysteriously absent.

 

Well, I just saw the difference in HCZ2, where Eggman's ship doesn't submerge to get the water spiral. But I can't find the difference in any LBZ2 boss, other than the game hanging at the final boss intro.

What I find the most interesting is the MGZ1 mid boss, which spawns the rotating spike pillar platform, only to prove Knuckles's jump height was decreased at this point in development (which I could play him though! Is there any code at all in S3 for a playable Knuckles?), but as MGZ2's path divider already proves, his jump height was planned. Just to see the rotating spike pillar shows that Knuckles was possibly playable at this point, which is more than just level design planning.

Just to show a screenshot of what I call proof of a playable Knuckles at this point in development for Sonic 3:

 

I always saw the spiked column as contributing towards the difficulty factor, as opposed to aiding Knuckles' jump height. All of Knuckles' bosses were made more challenging in some way, such as the dual LBZ1 bosses, the up and down mechanism of the ICZ2 boss always moving, the constant flame on the FBZ2 boss etc. From what I can tell, Knuckles could reach the MGZ1 boss easily enough, were it to come down to the same height as in Sonic's boss, but it seems to stop high to deliberately force the use of the column. Of course, it's merely speculation and I could be wrong, as it doesn't surprise me that Knuckles' game would be planned at this point. It was probably decided at the very start of production,, as he is a major character of the game.

 

And this is something else; most of S&K's bosses have no difference between Sonic and Knuckles. Only MHZ1 and FBZ2 have any difference at all. Again, it's like they completely forgot about Knuckles in S&K.

 

I think it's possibly emulator-dependent, because it's pretty broken, but if you enable it and then defeat the laser boss, the Eggmobile flies upwards instead of downwards, carrying some garbage tiles. It then flies across the screen from the left and causes a small explosion in the middle of the platform. In other words, it looks very much like a prototype of Knuckles' LBZ2 outtro.

Ah, I didn't realise it affected MGZ1 too - I guess I either forgot to check it or forgot what the results were.

The closest I know of is the codes already posted plus FFFF09:03 and FFFF0B:03 to catch the remaining character variables and enable the Knuckles signpost and got-through text. I can't remember if the jump height gets slightly nerfed with all that on too, but still no sign of climb or glide. And of course there are those old savestates that show his icon enabled on the save screen, but just starting from there without further interference doesn't even cause the effects from those previous two codes IIRC.

I don't know if there might be some other bytes somewhere that would activate other incomplete things - I only found that boss tweak by chance when I was porting over Sonic 3's final boss transition for Sonic 3 Complete, noting that both versions shared the same code at the point of the laser boss's death, except that a branch triggered by Knuckles' presence in S3K was triggered by FA81=1 in Sonic 3.

 

... back on topic, I wonder what the assembly code looks like for this cheat code.

Does it wait for button presses when certain music instruments are playing, at certain frames? Because that's how it seems to work, right?

 

IIRC, you have to press the buttons during certain frames.

 

Is this that code where you just grab on a swing at Angel Island, press Left-left-left-right-right-right-up-up-up-down-down-down, hear a ring SFX, go back to the title screen, and press up until you see "Sound Test"?

 

That's the Sonic 3 and Knuckles code, not Sonic 3's code. But that's what I usually do to listen to the music most of the time, sometimes I do the cart swapping method with plain Sonic 3.

 

That's S3K, and you don't need to press down at all.