A "Coming Soon" screen appears after a set amount of time, after finishing the boss battle or losing all your lives. No Game Over screen appears for the latter.
Main
You can boost in mid-air. This ability is available in the DS version of Sonic Colors, which uses the same engine as Sonic Rush.
The Boost meter can be refilled by running.
Boosting into the large Eggman wheel doesn't kill Sonic - he simply passes through.
Sonic doesn't react to being tapped on the Touch Screen.
Sonic's looking up animation is different.
The Jump Dash/Homing Attack is mapped to the Jump button, like most other Sonic games. In the final game, this move is mapped to the R button.
The Homing Attack has no afterimages.
You cannot pause the game.
Enemies don't go flying when you boost into them, they simply explode.
The "infinite boost" mode for maxing out the Tension Gauge is unfinished. The boost meter still flashes yellow, but boosting still drains the meter like normal. Sonic also does not flash yellow.
You don't get an extra life when you get 100 rings.
Boss Fight
No cutscenes play.
The Egg Hammer Mega takes only four hits to destroy. Two hits initiate the second phase.
The rolling head move is harder to dodge and doesn't have a "double" version.
The boss fight takes place on the Top Screen, with the Touch Screen constantly showing the Sonic Rush logo. In the final version, the fight takes place on the Touch Screen with Tails and the boss' health on the Top Screen.
Bug Fixes
A few bugs were fixed by the final:
When Sonic runs on slopes or jumps on bumpers, his model rotates incorrectly, often with his head down.
The infamous vertical standing glitch from Sonic the Hedgehog Genesis and Sonic 4 Episode I is very easy to perform in the demo, especially on loops.
The physics engine is slightly unfinished, and it is possible to get stuck when jumping against a wall until the momentum runs out.
Graphics
Icon
The icon that would display on the DS menu has a three pixel difference in Sonic's eyes.
Title
Proto
Final
The stripes appear on the top and bottom and have a 3D look to them. The background is a hexagonal pattern on a white background. The copyright text uses a different font and says "(C) 2005,Sega" instead of "(C) Sega Corporation, 2005". The start button uses a different font and style.
Boss Battle
The camera angle before the player gets control of Sonic is different.
The background music in this build is composed by Teruhiko Nakagawa and is similar to the musical style of the Sonic Advance games, as opposed to the pop-inspired style by Hideki Naganuma used in the final.
Song
Notes
Leaf Storm music. This song is reused for the Blaze Appear event song in the final, albeit considerably shorter.
Extra life sound. Doesn't seem to be used in-game, though.
Title screen music.
Boss music and its pinch variant. These songs sound rather similar to the track "True Area 53" from Sonic Advance 2, also composed by Nakagawa.
Stage complete music.
Sound Effects
The demo recycles voice clips from Sonic Advance 3, when Sonic was still voiced by Ryan Drummond.
Line
Transcript
"Yeah!"
"Waaahh!"
Levels
To do: Upload the maps.
Placeholder files for both Acts of all seven Zones from the final are present, but most are blank and unplayable except Leaf Storm Act 1, Leaf Storm Act 2 (which is normally available), Water Palace Act 1, and Dead Line Act 1.
Leaf Storm Act 1 & 2 - The most complete stages (along with the Leaf Storm Boss), with some differences from the final.
Water Palace Act 1 - Incomplete, but playable.
Dead Line Act 1 - Impossible to finish, with mostly garbled graphics.
Unused Sprites
To do: Compare with the ones used in the final's credits, and upload the patch here.
Sprites for Sonic and the Akatento badnik from Sonic Advance 3 can be found in the overlay files. These can be seen in-game by exploiting a camera glitch (which doesn't work in the final game) that causes Sonic's model to disappear for a split second, or by use of an IPS patch.
The sprites are mostly functional, barring some oddities:
Looking up does not trigger the appropriate animation, but ducking does.
Performing any tricks just repeats the spring animation.
The spindash sprites are misaligned, causing them to float above the ground.
Notably, the sprites used here are not the same as the ones in the credits, which use an entirely separate file and whom dust sprites are directly baked into the animation.
This prototype is documented on Hidden Palace.
