Throwing more people mostly making graphics, and creating movie like sequences where characters explain things isn't as hard with the tools available compared to making everything fit memory-wise making choices not faced today. Those three programmers interfaced with the hardware directly, solved os problems to get things working enough to put in a custom game engine they created into the smallest amount of memory before they can even start creating a world where there game could exist. The challenge today is how can I generate enough content to create a story to put into my unreal game engine. The 3d part, driver development, the memory management all is handled by something else.