Master System
Hardware

Play Built-in Maze Game:
Quickly Hold U+1+2 when the SEGA Master System logo appears.
Or Hold U+1+2 when you power on the SEGA Master System.
(NOTE: Does not work with all Master Systems)

Works with:
Master System Power Base (Hang-On & Safari Hunt, Built-in)

Does not work with:
Master System 2 (Alex Kidd in Miracle World, Built-in)
Master System 2 (Sonic The Hedgehog, Built-in)