Micro Machines (Game Gear, Sega Master System)

Micro Machines
Developer: Codemasters Publisher: Codemasters Platforms: Game Gear, Sega Master System Released in US: March 1994 (Game Gear) Released in EU: March 1994 This game has uncompiled source code. This game has hidden developer credits. This game has debugging material. This game has a hidden level select.

Checksum Test

Game Gear	Master System

Hold Up + 1 + 2 when powering on the system and the game will perform a ROM checksum test. Once it's complete, the ROM checksum along with the game's build date (in DDMMYY format) and time will be shown. If the checksum test passes, a smiley face on a green background will be displayed.

If the checksum test fails, the game will display a dead face on a red background and play a constant buzzing tone.

(Source: SMS Power!)

Track Select

At the title screen, press Up, 2, Down, 2, 2, Left, 2, 2, 2.

(Source: GameFAQs (samjustsogoodatddr))

Hidden Credits?

Starting at around offsets 0x3FEA6 in the Game Gear release and 0x3FEA1 in the Master System release is what seems to be a set of hidden credits:

JON THE PROGRAMMERS' - SQUINKY
BIG RED S CO.

(Source: idrougge)

Uncompiled Source Code

Several small fragments of source code can be found at offsets 0x26, 0x54 and 0x71 of the cartridge data:

Game Gear	Master System
****************	P HL INC HL LD
LAY EQU 0 ;a delay	(CH2MAP2+9),A L
EQU	9),A