[Ambil]

Back in 2005, I remember saying S2 was built off S1, just by looking at level slots. Stuff like GHZ was slot 00 on both, etc.

Now I know to hack level layout in both ROM and savestates, and I discovered one of the most bizarre programming holes in S2 SMS.

After reviewing, by normal gameplay, all levels of S2, I realized there are no bottomless pits at all. There are spikes everywhere they should be, even in Sky High Zone.

See, as example, this hacked savestate of Gimmick Mt. act 1. I remove all standard solid blocks from layout. If you fall to the bottom of the screen, you will find a surprise.

Note: This package includes two savestates, ".s00" for MEKA and ".ss0" for Fusion. Savestates will only work if your ROM is named "Sonic the Hedgehog 2.sms".

Attached File(s)

•  Sonic_the_Hedgehog_2.zip (19.68K)
  Number of downloads: 5

This post has been edited by Ambil: 04 May 2008 - 07:14 AM

[Ambil]

Nobody cares about my research, as usual. But I'm not out to let this go without giving results.


Sonic is about to fall in the hole...


And he finally falls. But he doesn't die?!


The screen starts scrolling up instead.


It stops scrolling at some point you can move Sonic horizontally -- though you can't see him, the camera moves.


At certain point after moving Sonic, the camera scrolls up again...


...until a point you can't move anything more. Time for a restart.


I repeat, this will _never_ happen in normal gameplay, since there are no bottomless pits.

This is PROOF S2 wasn't made out of S1, and all the rest is bullshit.

[Krigo]

Pretty good work, I guess GHZ was the first level to be programmed into the game. To tell the truth, I never thought Sonic 2 was built on Sonic 1, sure there isn't many differences, but what's the point in re-using an engine when you can build a better one?

This post has been edited by Krigo: 02 May 2008 - 04:57 PM

[JoseTB]

Well it's interesting, I don't think it's been mentioned before.

Ambil, on May 2 2008, 11:31 PM, said:

This is PROOF S2 wasn't made out of S1, and all the rest is bullshit.

But you know, programmers might felt like being creative and actually implemented that for S2 and everything. I'm guessing that wouldn't involve more work than, say, the spike bugfix on the genesis series.

[Ambil]

Krigo, on May 2 2008, 11:56 PM, said:

what's the point in re-using an engine when you can build a better one?

$$$

Saving time and money by not programming a new engine, if you don't get it.
Only some details have been changed in the engine (example: roll and jump faster).

JoseTB, on May 2 2008, 11:58 PM, said:

Ambil, on May 2 2008, 11:31 PM, said:

This is PROOF S2 wasn't made out of S1, and all the rest is bullshit.

But you know, programmers might felt like being creative and actually implemented that for S2 and everything. I'm guessing that wouldn't involve more work than, say, the spike bugfix on the genesis series.

See above. This isn't the only difference -- I highly doubt programmers would waste time (and therefore I doubt Sega would waste money in programmers) just to delete the death by falling to pits, nor to delete the checkpoint monitor, nor to delete the shield monitor, nor to delete the island map, and the list keeps going on.

Remember this game was developed MORE in the rush than its homologous for the Mega Drive: it was released only 10 months after Sonic 1.

[ICEknight]

Makes sense, since only Sonic 1 was made by Ancient. Nice observation.

[nineko]

Sonic 1 and Sonic 2, however, share the complete set of sprites iirc, except for the sprites added in Sonic 2. They only have a slightly different palette.

[Overlord]

Nice work - I know I didn't check this out until now because of the hassle with fiddling with the savestate =P

[muteKi]

Right -- I only use Fusion.

[Ayla]

I remember you talking about this in IRC the other day. Fascinating =)

[Ambil]

muteKi, on May 4 2008, 04:46 AM, said:

Right -- I only use Fusion.

You want a Fusion savestate? You got it, in the first post.

Anyways you can do this with the same method.

• Open a savestate your savestate in a hex editor.
  
• Go to offset $6E (in MEKA) or $40BD (in Fusion).
  
• Select a block of size $1000, cut it and paste it in a new file.
  
• In the new file, replace all instances of the default solid block (usually $29) with $FF (empty block)
  
• Insert the new $1000 file into the savestate file, in the same offset.
  
• Save the file.
  
• Turn power back on and... ENJOY!!!

Ayla, on May 4 2008, 04:54 AM, said:

I remember you talking about this in IRC the other day. Fascinating =)

if(Ayla>=3)
 Ayla=2.9999;

Thanks to all of you for your comments.

> Apart from this, just out of curiosity, look what I found hacking a Sonic 1 SMS savestate from Fusion.
Offset $160.

.x0x.|0|L|0|L|0|L|0|Lx0x........

Steve Snake is obviously a turd. lololol

[Rolken]

If you haven't seen it, you might be interested in this topic. Sonic 2 and Sonic&Tails 1/2 and Sonic Blast were all based on the same engine, being by the same developer (Aspect) as opposed to Sonic 1's developer (Ancient).

Krigo, on May 2 2008, 04:56 PM, said:

Pretty good work, I guess GHZ was the first level to be programmed into the game. To tell the truth, I never thought Sonic 2 was built on Sonic 1, sure there isn't many differences, but what's the point in re-using an engine when you can build a better one?

Programming an almost identical engine from scratch is something that pretty much never happens unless there's a very compelling reason to do so, such as a radically different platform. Why burn time reprogramming the same things you've already done?

edit: also Sonic 2 appeared to be the only game in which the map loading was completely stupid and had no concept of a level bottom, and would load whatever garbage it saw until it ran out of map space. That probably has something to do with your wandering around below the level shenanigans.

This post has been edited by Rolken: 04 May 2008 - 10:37 AM

[Ambil]

Rolken, on May 4 2008, 05:35 PM, said:

If you haven't seen it, you might be interested in this topic.

Why didn't you tell me before about that? :P I would never have imagined somebody would bother in creating full level maps of the so-hated game.

These level layouts can now be imported into SonED2 using my method. Indeed, much better and useful than my block maps and block sheets (not released yet).

Now I don't have to cry anymore for the work I lost in my original project to port this game as-is into the Mega Drive Sonic 1, thanks to this and Hayate's new utility.

Rolken, on May 4 2008, 05:35 PM, said:

edit: also Sonic 2 appeared to be the only game in which the map loading was completely stupid and had no concept of a level bottom, and would load whatever garbage it saw until it ran out of map space. That probably has something to do with your wandering around below the level shenanigans.

Well, makes sense that some of the levels have all their bottom line filled with spikes. Something I knew after creating my block maps... just wondered what would happen if reaching the end of a level that has no spikes.