I've been working on this for a couple of hours, but here's a changelog and a few screens.
Prototype 611
- Sega Titlecard plays
- Game Begins
* Rom is half the size as the following ones, perhaps because Knuckles was not yet implemented / removed
Prototype 74
- No Sega Titlecard plays
- Game starts with level select
- Text based character select
* Major Difference: Debug Mode - Holding 2 will freeze character and allow the player to move him freely with the D-Pad
Prototype 806
- No Sega Titlecard plays
- Game starts with level select
- Text based character select
* Also includes Debug
* As far as I can tell, it's the same as 74
Prototype 821
- Sega Title Card plays
- Introductory cinematic plays
- Game Titlecard
- Level Select
- Graphical Character Select introduced
- Level Titlecards
- End of level placards actually now
- End of level titlecards play now
* Still has Debug
Prototype 827
- Sega Title Card plays
- Introductory cinematic plays
- Game Titlecard
- Level Select
- Graphical Character Select introduced
- Level Titlecards
- End of level placards actually now
- End of level titlecards play now
* Debug has been removed from being default
Prototype 910
- Sega Title Card plays
- Introductory cinematic plays
- Game Titlecard
- Graphical Character Select introduced
- Level Titlecards
- End of level placards actually now
- End of level titlecards play now
* Level Select has been removed from being default
Prototype 94
- Sega Title Card plays
- Introductory cinematic plays
- Game Titlecard
- Graphical Character Select introduced
- Level Titlecards
- End of level placards actually now
- End of level titlecards play now
* Essentially the same as 910
Level Select Menu

Text-Based Character Select used in protos 74 and 806

Fun with the debug mode
