(GG) Sonic 2 Auto Demo Prototype (1991-12-05) - Info & Download

Wow, this is awesome!

This game was clearly rushed. Look at how much it was clearly stripped down from the design intentions of this build. Sonic also controls like utter shit. Honestly, I've always felt that Aspect did a poor job with this one. Chaos was more tolerable, and Triple Trouble was actually pretty neat. I especially like Tails Adventures, but they dropped the ball with Blast.

It is pretty fun to look into the vastly different levels. I find it amusing how Sonic disappears behind the lightning due to it simply being a palette cycling effect. Being behind the rain makes it feel less flat and "pasted on", but I can see why they changed it.

 

Come on, Crackers was at least relatively playable :P Except for that goofy carnival level with the inverted loops and non-existent collision detection for the ground ¬_¬
[youtube]http://www.youtube.com/watch?v=yryaufVjwQA[/youtube]


I'm pretty psyched to see what people do with this proto... I'm hoping for levels to be imported into the final version

 

So, here's the recap of all the "official" levels in this ROM. There are more, of course, but I'm only listing the ones that are played automatically during the auto-demo.

Zone 4 Act 0 - Intro with running Sonic
Zone 4 Act 1 - Title Screen

Zone 0 Act 0 - First Stage
Zone 1 Act 2 - Second Stage
Zone 3 Act 1 - Third Stage

The SEGA screen and the COMING SOON screen are not Acts they are just screens on top.

 

If it helps, here are the memory addresses for Sonic's Coordinates. Might be useful in Sky High, since there was some floor after the hang-glider section that you normally see during the demo.
X Position: 1510
Y Position: 1514
Scrolling is handled with a different address and changing the position won't auto-scroll there, so you're better off freezing these or making minor changes if you just want to explore.

 

I did an hours worth of streaming just fucking around the levels and generally fucking around with the ROM.

 

Also if you set the byte 0x2BA (some parameter to be pushed into the sound driver) to 03, you will see a strange debugging screen saying ACT 1 ZONE 1. Just thought it would be interesting.



LATE EDIT: Oh my, turns out I gave out the wrong offset. Fixed it now.
Here's the disassembly of that position. Apparently this part determines ROM mapping, according to MarkeyJester:

Code (Text):

1. ROM:02B9                 ld      a, 2
2. ROM:02BB                 ld      (byte_FFFF), a
3. ROM:02BE                 call    sub_8000

 

Just got to the part where you're trying to use Regen's memory editor.
I would suggest BizHawk if you want memory search and editing on GameGear. It can also disable the GG borders. That's what I used for the addresses posted previously in this thread.

 

Ah god dammit. Just what we needed. A bit late now, but that's good for future reference.

 

Using Aspect Edit, Sonic's uncompressed sprites are located at offset $10000, these are his GHZ sprites. Next his SHZ sprites are located at offset $14000, then at offset $18000 you can find his loop sprites. Next at offset $1C000 is the HUD's compressed art, next at offset $20000 you can find the intro's compressed sprites. Finally at offset $28000 is where the early title card text compressed sprites are located at. Not much but meh, you can edit some of Sonic's art and various other art now. xP

 

Call me when we have level maps! :P

 

This is pretty much 'the' biggest proto find since the Simon Wai beta, I think?

Seriously neat stuff here...

Oh, and you can roll forever. In both directions, back and forth. Without stopping.

Can we get some youtube content up of the other levels? How many working ones 'are' there in this?

 

Wouldn't that be the Sonic Adventure Autodemo?

 

Let's see... two-way loops, strangely-shaped tubes, curved ceilings and fortresses in Underground, a few broken bridges in Sky High, an already almost-final Green Hills boss level and... horrendous physics.

Awesome!

 

I'd say that's the second biggest because of Windy Valley being the major change.

Here we have more than just a single "Zone" changed

 

Seconding this, I want to see these levels in their entirety. The way a lot of the already known unused content is actually used in the demo is exciting to find out!

Thanks for making all this possible Orengefox!



+ - I still prefer this Green Hills Zone design over the one in-game.  

 

My stream covered all playable zones, but hitbox does not seem to want to do proper playback, at least for me. Probably not the most ideal means of seeing every zone.

 

Have you been able to successfully "push to youtube"?

I've managed it with the SAGExpo logs for the most part, sans a couple. I know it's a very finicky feature, though.

 

Wow, no wonder it's so messed up, if it was nearly complete this early into the game. That one definitely needed a retouching to match the rest of the game.

 

Amazing stuff Orengefox - glad to see this released! My PC's back in action, so I'll be grabbing this when I get home and checking it out - as well as catching up properly on everything people have dug up out of it so far! = )

 

Put me on the list of people who want to see maps. It's a fascinating release to be sure.

Also Sonic the Hedgehog 2 (8-bit) AutoDemo

That's probably because apparently only the concave tiles survive in the final ROM, not the convex ones.