To do: Get accurate version of Final demo from bsnes-plus.
Both prototypes are missing the prologue cutscene.
The early prototype plays no music during the title sequence.
Early Prototype
Later Prototype
The older prototype only has "GAME START" as an option. Plus, both prototypes say "sample." That's another difference right there.
Both Prototypes
Final
The early intro stage demo plays from the start of the stage to the Gigantic Mechaniloid fight. The final game's demo starts at the Gigantic Mechaniloid fight.
Morph Moth Demo
Wire Sponge Demo
The sample versions have two extra demos for Morph Moth and Wire Sponge. These demos were likely recorded for the Summer CES 1994 build (which only featured the intro and these two stages), and as a result the demos no longer sync up with the layouts in either prototype: for Morph Moth, the desync occurs at the Old Robot fight's entrance, while in Wire Sponge's stage, the desync occurs in the first Sole Solar area.
Password
The password screen is normally inaccessible in the early prototype. Use Pro Action Replay (PAR) code 7E003C01 on the title screen and select "Game Start" to access it.
Mega Man X
Early Prototype
This early password screen has its sprites set up like the screen in the first game -- complete with glitched Metalls -- but the graphics are new and they were already planning to expand the grid from 4x3 to 4x4. The game uses the sprite palette from X1 here, which doesn't fit with the new password digits; the correct palettes are stored in the ROM from 0x02C9A0 to 0x02CA1F and are identical to the four palettes in the later prototype. Passwords from both X1 and X2 are incompatible with this prototype, and it's currently unknown what passwords do work, if any.
E. Prototype
L. Proto + Final
Though the graphics are glitched on the screen, the images of Zero and Serges that indicate a correct or incorrect password respectively are already in the ROM and loaded to VRAM. Serges's graphic is identical, while Zero's graphic was redrawn to look less cute.
Early Prototype
Later Prototype
Final Game
By the later prototype the 4x4 grid was implemented and the sprites were set up like in the final game, though the border, background, and password digit graphics are all different. The password system itself is close to the final version, but isn't quite finished yet. Notably, the password that would normally start the player at the last Sigma stage in the final game (6474-6557-6788-7223) is rejected in the prototype.
Under certain circumstances, the password system also seems to be capable of producing passwords that it won't accept.
Options
Early Prototype
Later Prototype
Final Game
This is normally inaccessible in the early prototype - use Pro Action Replay (PAR) code 7E003C02 on the title screen and press Start to access it.
It's inaccessible for a good reason: It's completely unchanged from the first game! The "OPTION MODE" graphic is no longer in the ROM, so the game displays a collection of garbage tiles instead. The button assignments and sound test still work, though.
The action text, sound option, and exit text use a darker palette in the later prototype. The gold borders were rounded out a bit for the final version.
Intro Stage
Stage Graphics
Both Prototypes
Final Game
A few of the tiles in the mountainous background were touched up for the final game. Note the shading on the border of the large dome-like mountain and the tiles that connect the mountains to the lower part of the sky.
Both Prototypes
Final Game
The shading on the top of the rocky tiles at the start of the stage is darker in the final version, and the sand dune is slightly smoother.
Early Prototype
Later Proto + Final
There's a problem with one of the 256x256 blocks in the early prototype. This block, the one on the middle, is designed to connect with the one on the left. The problem comes when it's repeated twice in a row: The railings on the bottom look okay, but the one in the middle is connected to nothing and the one on top doesn't properly hook up with the bridge to the left. Later versions shift all the graphics in that 256x256 block to the left, then extend the railings further right to make up for the lost space.
Layout
Both Prototypes
Final Game
This Scriver (the very first one in the game) was removed in the final version.
Both Prototypes
Final Game
The final game redraws the floor tiles and the pipes and accoutrements and such on the walls and ceiling.
Both Prototypes
Final Game
There are fewer platforms and ladders in the prototype. The platforms go up higher in the prototype, putting the player in direct line of contact with the Gigantic Mechaniloid's head. Easier to hit, but easier to take damage too. The final version lowers the platforms, forcing the player to jump and fire unless they go to the platform at the top-right.
Miscellaneous
Early Prototype
Later Proto + Final
The background starts at a different offset in the early prototype.
Beating this stage in the prototype shows a password screen. In the final game, the password screen only shows up after the X-Hunter cutscene plays.
In both prototypes, the player can pause during the opening ride chaser sequence, something not possible in the final.
X-Hunter Intro
This cutscene does not exist in the older prototype.
Later Prototype
Final Game
The X-Hunter silhouettes are missing.
No music plays during this cutscene.
The darker palette that the final version uses for this cutscene doesn't exist yet, so the standard Central Computer stage palette is used instead.
Holding the Y button during this cutscene will cause X to charge his X-Buster. This was corrected for the final version.
Weapons Menu
Early Prototype
Later Prototype
Final Game
The early prototype's weapons menu uses a different design than the later prototype and final game. It's a set of borders inside a border inside another border. In the later prototype and final game, the weapons menu use the same tileset as the password screen, so the same differences apply.
The unselected items are brighter than they are in the final game, and the "Exit" option is lower on the screen.
The "EXIT" graphic reuses the graphics from the first game in the early prototype. Since having a graphic that says "EXIT" above text that also says "EXIT" is redundant, the graphic was changed.
The ends of the meters are one pixel wider in the early prototype.
The Giga Crush and Item Tracer use the standard energy meter in the older prototype, while in the newer prototype and final game they use unique blue meters.
The Item Tracer is called "Search R" (Search Radar?) on this screen. In the early prototype, the graphic uses a placeholder "10" icon on this screen only.
The space where Zero's parts would be is taken up by an X2 graphic in the older prototype. Though the graphics for Zero's parts are in the newer prototype ROM, they never show up in that space.
Stage Select
Early Prototype
Later Prototype
Final Game
The final game removes the "DATA" from the stage info toggle.
The large gray building in the middle-left is labeled in both prototypes. In the in the early prototype it's "E.H" (presumably misromanizing the character "イ" to an E instead of an I) and "I.H." for Irregular Hunters (named Maverick Hunters in the international releases) in the later prototype. The label was removed in the final version.
After defeating three Mavericks in the later prototype, the Maverick Hunter building is destroyed. In the final game, if the player doesn't collect all of Zero's parts, there's a cutscene that explains that one of the X-Hunters stormed the base and stole all of Zero's parts back (including his control chip), but there's no visual indication of this. It's possible that the building should have been destroyed after defeating two Mavericks, not three, since that's when the X-Hunters show up.
Both prototypes are missing the cutscene that plays after defeating two Mavericks, and the one after all eight Mavericks.
In the early prototype, defeating all eight Mavericks will not change the stage select screen at all. In the later prototype, the X-Hunter Base button will be added to the stage select, but it cannot be entered.
Early Prototype
Later Prototype
Final Game
The X-Hunter map palette doesn't get as dark as it should in the early prototype.
The X-Hunter base has a different design in the early sample.
There are a few coloring errors on the X-Hunter base in both prototypes -- check out the pink pipes in the bottom-middle of the image -- though the newer prototype fixes a few of the ones from the older build.
Later Prototype
Final Game
The graphics for the destroyed X-Hunter base aren't in the early prototype.
The destroyed X-Hunter base has the same coloring errors and introduces another one by coloring the green tower pieces yellow.
Early Prototype
Later Proto + Final
The cursor's cycling palette is different in the early prototype, transitioning from teal to cyan to orange. This was changed to a more natural magenta to pink to orange cycle in the later prototype.
E. Prototype
L. Proto + Final
The map points changed from teal to pink too, but the light rotation changed as well. The early prototype has more frames than the later prototype, but the light never directly "faces" the screen. The final version added a straight-on frame but had to delete one of the rotational frames to make the light rotate properly.
Early Prototype
Later Proto + Final
The static sprite overlay is brighter in the early prototype.
E. Prototype
L. Proto + Final
Though the X-Hunters never appear on the world map in the early prototype, those sprites are in the ROM. Agile and Violen are particularly different, while Serges only went through minor shading and color changes.
Text
Early Prototype
Final Game (JP)
WEATHER CONTROL STAGE
BOSS : Wire
Hechimale
WEATHER CONTROL
STAGE
BOSS:
WIRE HETIMARL
DUST STAGE
BOSS :
ROBOT SCRAP
STAGE
BOSS:
METAMOR MOTHMEANOS
VOLCANO STAGE
VOLCANIC ZONE
STAGE
BOSS:
FLAME STAGGER
CPU STAGE
CENTRAL COMPUTER
STAGE
BOSS:
MAGNE HYAKULEGGER
DESERT STAGE
DESERT BASE
STAGE
BOSS:
SONIC OSTREAGUE
SEA STAGE
BOSS : Bubbly
Crabross
DEEP-SEA BASE
STAGE
BOSS:
BUBBLY CRABLOS
TANK STAGE
DINOSAUR TANK
STAGE
BOSS:
WHEEL ALIGATES
CRYSTAL STAGE
ENERGEN CRYSTAL
STAGE
BOSS:
CRISTAR MYMINE
SIGMA STAGE 1
COUNTER HUNTER
STAGE
BOSS:
??????????
While the early prototype doesn't display text on the stage select, there is some preliminary stage info in the ROM starting at 0x027770 (and repeated at 0x0279CD.) Every stage but the first uses a preliminary name, only two bosses are named, and both of those bosses use different romanizations than the final game. The X-Hunter / Counter Hunter Base is labeled "Sigma Stage 1", which suggests there would be multiple labels, but the later prototype and final game uses the same label for each X-Hunter stage.
In the later prototype, the centipede boss is called "MAGNA 100LEGGER" on the stage select and "MAGNA HYAKULEGGER" on the Maverick intro screen. The larger font that the Maverick intro screen uses doesn't have a 1 or a 0 in it; instead of adding those to the font, the developers just changed his stage select name. Both names mean the same thing anyway.
Boss Intro
The early prototype doesn't display boss intros; closer inspection of the code reveals that the Maverick names and intro code are identical to the first Rockman X.
Early prototype
Later prototype
Sigma's sigil and the beam of light (or whatever that is) are brighter in the later prototype.
The background is laid out differently; the early background also has a cycling palette that was removed in the final game.
