Hello again, Code Ninjas! It has been quite a while since Part I, but never fear - slowly but surely I will give Sonic Genesis the drubbing it deserves. Welcome to The Nitpicker's Guide to Sonic Genesis - Part II.
Code Flaw #002: The Demos Are Totally Nerfed
The demo is completely different in the GBA version, and obviously much worse (Sonic is hurt twice, seems disoriented, and demonstrates less of the level). Why should this be? If we were uncharitable, we might chalk it up to the GBA team recording new demos which betray their underdeveloped skill level. However it is much more likely that the game is using the same demo data, but changes in the physics have thrown it off.
You see, the demo "movies" in the old Sonic games were not actual videos of the action - that would have taken up so much space it would have been prohibitive. Instead, the game itself is running, but with two changes: 1) the game resets when the player hits the start button or when 30 seconds have elapsed, whichever comes first; 2) the Sonic object isn't receiving input directly from the joypad, but from a chunk of data read sequentially from the ROM. This chunk of data was made by logging the button presses while someone played the level (for more information about recording joypad input "movies", see this post).
So, if the physics or level layout changes, the recording won't be appropriate anymore. It's as if your joypad were simultaneously plugged into two Sega Genesises (Geneses?), one of which contained a Sonic 1 cart, and the other, Sonic 2. You might be playing Sonic 1 beautifully, but anyone watching the Sonic 2 game will wonder why Sonic is suddenly acting like a drunkard. (They won't notice a difference in Tails' behaviour, though - wantonly flinging himself into harm's way is business as usual for him. =P )
The team who made Sonic Genesis should have recorded new demos after the physics were in place to avoid this issue. But, one can hardly blame them for not doing so; it would, after all, have involved playing the game, and I wouldn't wish that on anybody!
Fixing The Problem In Your Own Hack
This issue with screwy demos isn't confined to Sonic Genesis. ROM hacks will have the same problem if the physics, controls, or layout are changed, even slightly. I encountered it myself when making Sonic: The One Ring, and needed to find a way to record new demos that would be compatible with the ROM. I've turned what I learnt into a tutorial and utility - go here for the complete story. See, I'm not just complaining about Sonic Genesis just to be mean - I'm using it to frame programming tips to help you guys out! Aren't I nice?
Well, not that nice since I'm now going to throw in a few freebie Bonus Flaws out of spite!
Bonus Flaw #003: Wrong Credits Footage
In addition to having broken demos, the "demos" seen during the game's credits are broken, too. But none so badly as the Labyrinth Zone one: this time, not only does the control movie not sync up because of different physics, it's totally inapposite because the wrong area of the level has been loaded!
The famous underwater section where Sonic is pulled through the tunnel by the current, catching on to the breakable poles and avoiding spikes, has been inexplicably replaced by some other region of the zone.
Bonus Flaw #004: Marble Zone Button Keeps Turning Up Like A Bad Penny
This is pretty hilarious. It's supposed to load different graphics depending on the zone ID, but they can't even get that right.
Bonus Flaw #005: Underwater Palettes Incorrect
Sonic and the Badniks don't look right...
...but objects like doors and blocks fare even worse.
(And why does Scrap Brain Act 3 have such a horrible dark blue background? It's supposed to be a lovely, rich purple.)
Bonus Flaw #006: Missing/Incorrect Background Tiles
This flaw really does take the cake. This isn't a matter of not being able to properly port a complicated game's physics to a new platform, or something relatively forgivable. It's a simple matter of gratuitous incompetence and unconcern for the product.
Well, try to keep your lunch down, Code Ninjas - I know it's not easy after that rogue's gallery. Until next time!