Sega Master System / Mark III / Game Gear
Sega8bit & SMS Power! 2013 Event - 10th August 11 weeks and 12 hours from now
Black Belt uses the R register to place enemies on the screen. If R register is stuck to 0, only the "bosses" will appear.
The level select "counter" variable is located at address $DB6B. Write $12 to this location to activate level selection (then you can select a level with controller 2).