Metal Head prototypes
There are currently ten prototypes available for this game. In addition to the ones below, there are also prototypes for the 13th, 14th and 20th of December that need further looking into. Actually all of these prototypes need more looking into, as I imagine some of the levels are different (and the earlier prototypes might even have more levels, as their sound tests list music for a seventh and eighth stage -the final only has six stages) but I really don't care for this game.
-The SEGA logo has someone shout "SEGA!" using the same voice clip from Sonic the Hedgehog.
-The intro has both English and Japanese text.
-The title screen is slightly different, featuring no copyright info, and pressing start takes you straight to the first level -there is no options menu.
-There are no stage/mission title screens.
-During the mission briefing, the words are not read out.
-Some of the briefing text is different, and would be altered in later prototypes.
-There is no music during a mission briefing.
-The game doesn't support the six button controller yet.
-Explosion sprites don't appear when hitting/destroying enemies.
-There are no score screens after a mission ends. However when you enter the shop you'll have a lot of points to spend.
-The shop isn't fully complete yet, as you can't buy certain items.
-The SEGA logo has a new animation, featuring lots of colors. The Japanese final version would end up keeping this, however the American and European versions would not.
-During the intro, the HUD has some numbers above the "MISSION START" text, which change throughout.
-The title screen now has copyright text and a menu, letting you start the game or go into the options menu.
-The options screen lets you set how many continues you want (up to five), there is no language select, the sound test is missing some pieces of music or has different names for them, and the piano keys are mis-colored.
-The stage/mission titles are now present.
-During the briefing, the background used in the picture of your superior has been changed, and matches the final version.
-Some of the text has been updated and reads better than before.
-The numbers above the "MISSION START" text at the intro have been removed.
-The intro now only English text.
-The continue select has been removed from the options menu, and replaced with a language select. The BGM test has been updated, with some tracks having the wrong names. The keyboard now matches the final version.
-There seems to be a problem with the options screen, as the bottom of it features glitchy graphics.
-The six button controller is now supported.
-A new voice now says "SEGA!", this was kept for the final game.
-The BGM test has been updated yet again, and is now closer to the final version in terms of track names.
-The graphical glitch in the options menu has been fixed.
-A lot of speech has been added. During a briefing, the text will now be read out by your superior.
-The SEGA logo has been changed back to what it was in the first prototype (and final American & European versions).
-The BGM test now matches the final version.