Step 1:Idea
Its just an electronic game like a traditional game boy but with different component like arduino, lcd,some buttons and for more features speacker to add some sound and excitement to the game
Step 2:Packging and body outline
custom game boy is square shaped, but is it the most suitable shape! i don't think so.
so we think about packging contains all compnents from inside and easy to be held out side.
Mainly i think 3D printing would be grate to be convinent with all requirements of the design
Step 3:components
Obviously it requires some sort of micro controllers, as arduino is the most common used microcontroller but actutally we don't need all faetures in arduino, also we need a spacial design conatins all components on the same board
so designing a one Pcb contains the microprossor and the interfaces would be si grate!
Interfaces are like Oled lcd, Push buttons, speacer, on/off switch