Video game development is probably the wrong skill for GPU design - you might be the best racing car driver in the world but that doesn't mean you know how to design an engine.

If you've a few spare billions and a chip design, I'm sure a semiconductor fabricator will start running off the chips for you. The design is tough:

• lots of memory cache, which is the same simple thing repeated billions of times

• a shader core, which is essentially a simple cpu specialised in floating point, which you will then repeat thousands of times. Needs to be efficient, though, and the smaller you can make it the more you can repeat it

• some extremely complicated interconnects and management circuitry, such that all your shader cores can read and write memory fast enough so that they can run at full speed

• you'll also need driver code to enable your new chip, implementing all of the DirectX, OpenGL and Vulkan specs, and tested against decades of games

There was a time when chip design was a one-man job. Alas, that time was the late 70s. And your goal wouldn't be to reproduce one of the early graphics cards from the late 90s either, much as I did love my Rage Pro 128 at the time. If you want to make something competitive with modern GPUs that can run modern games, you're going to need a very large team of specialists and a lot of funding cash. Intel have been trying to do this for a decade, and they're just catching up with NVIDIA and AMD now.