and heres a sketch done by  kingofacesx, which the extra features i suggested.
Current Features:
Front digital display: With and 8 bit mono speaker to go with it! this displays mar's health and status. there would be a pair of buttons near the bottom or side, so any one but mar can change a few settings.

PowerSupply: mounted to the side, this power the full unit, and if the batteries go dead, mar gets very sluggish, weak, and may faint or even go into coma if he doesn't get fresh AA batteries quickly.

Cartridge Reader: using the most advanced gaming systems of the 1990's! This buger can read any cartridge's program, though it is proze to freezing, glitches and errors! Blow in slot to remove bugs!

Rear Genetic alternator. This is where all the science comes in! this little machine is what directly changes mar's DNA, body, or brain!

For any one interested in a bit of the backstory on this device, when both Mar and Fae where kids, some one forced Fae into a tight spot, and forced her ingenious mind to create some kind en-slavery device. Fae used their own gaming system to create the device, and attached it to mar as a test subject. lets just says things did not go to plan after that.