Super Mario Bros 8 bits:
1 - First, buy a box of Lego Basic Parts, 325 pieces.
2 - Use this image as a reference. Note that it is composed of equal size rectangles.
3 - Each rectangle in the image above is a 4 pins Lego block . The box will have varying size Lego blocks, but by combining blocks of 2, 4, 6 and 8 pin gives you a way. Despite stocky, because the blocks are more horizontal than vertical, the result is cool :)