Retro FPGA game engine

From an educational perspective:

Is it possible to create a complete game in FPGA (pure HDL)? I suppose it is, I know it is... ;-)

There are of course different levels of game... pong can be created without too much code, more complex games will need more effort.

I would like to create a list of things needed for a more complex game.

What are the skills needed for a retro game engine implemented on an FPGA board?

Which knowledge has to be acquired?

    How to draw on a screen, lots of VGA tutorials out there.

    How to draw lines, more theoretical, bresenham algorithms etc.

    Loading images/sprites from an SD card or via ethernet, getting more complicated...

    Swapping sprites in memory

    I am thinking of DMA for double screen buffering, video signals, HDMI, ...

Which are good learning resources?

Lots of VGA tutorials out there, but I don't have the impression there are many HDMI tutorials, is this so much more difficult?

Let's discuss what levels of knowledge are necessary and try to build up a structured set of skills one should develop step by step.

This could lead to a series of HDL tutorials for the intermediate to advanced learner...

Tell me what you think.

Message was edited by: Yuri Cauwerts to clarify a bit more the intention of this question.