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

Good job OrengeFox.

I was worried they might all be final builds, hopefully the Sonic 2 prototype will reveal some interesting stuff.

 

Just want to say thankyou to everyone involved for making this available and preserving Sonic's lost history.

 

Thank you for this release and also thanks to all the people who contributed!

 

Wow! That Sonic 2 prototype is so different...

Glad to see that more prototypes have been uncovered!

 

I must point out that this has produced a cleaner version of this:

Well... except for things being realigned between these builds.

 

grrrr... why or why did I have to be at work when this happens. Can't wait to get home.

 

Well I converted the ROM to a SMS file so the resolution is bigger so we can see things that aren't normally seen on-screen, of course this corrupts the palette data but lets us see the things that are off-screen in this Demo.
We can finally have a better look at those bigger trees in Green Hills Zone.

[media]https://www.youtube.com/watch?v=kQYyYtHpKDo[/media]

 

Thank you so much. <3 I just came home from hanging out with a friend, scored some pretty awesome merchandise from the mall and now this! Even though I have to go back to work tomorrow, today's been a pretty cool day. Time to dig into the Autodemo. ^_^

 

Thanks for your dedication, Orengefox!

You can achieve the same thing without any modification to the ROM or loss of palette data by enabling "GG FullSMS" in Kega Fusion's configuration dialog.

 

Thanks for informing me on that Hendricks 266. Here is the game in GG FullSMS mode. Basically a version of the video I posted a few minutes before but with the correct colors.
[media]https://www.youtube.com/watch?v=KXxjRy0rULI[/media]

 

A few notes I've picked up so far:

Offset - Decription

0B0D - Sonic's art updating routine
13D8 - Sprite flush related
26AD - Scroll flush/control related
8000 - Sound driver

This next part you WILL be interested in:

042F - The scene control routine.

This is a list of calls to each screen that's to display in order....

042F - 0431 = Intro (Sonic running in the emblem)
0432 - 0434 = Title screen
0435 - 0437 = First "Tropical/GHZ" level
0438 - 043A = Second "Sky High" level
043B - 043D = Third "Underground" level
043E - 0440 = The "Coming Soon" screen
0441 - 0452 = A repeat of above.

I'm gonna find the control locking routines wherever they are, and see if we can remove the demo control and allow us to explore further.

EDIT: Found it, offset 0705 is what's controlling Sonic to move, jump and hold down for rolling, specifically.

 

I went ahead and recorded a higher quality version of the Sonic 2 Auto Demo.



I also recorded brief gameplay footage of the Tails Adventures and Sonic Labyrinth Pre Releases.

https://www.youtube.com/watch?v=pb2a1UQ2hjc
https://www.youtube.com/watch?v=yz7Y6YzfyZM

 

So there seems to be only one song indexed, the one that plays through the demo at ID #83 You can check this going to Addres DE03 and changing the value. It has some SFX unused in the demo too!

 

[url="http://mrjester.hapisan.com/01_Public/S2GGB%20Control%2002.gg]Download[/url]

Get exploring retro! Demo time is now removed, and you now have control over Sonic.

Edit 02: HAH,. there are spikes and functional springs on the level!

 

Jeez you're fast! Thanks!