Igor, This is a subject area that seems like it would be a good starter learning project and doable but really its not.

There are many problems that just are not suited to a young person at that age level of comprehension. Gaming graphics for example often requires understanding quaternion math, computer science, and hardware at a very low level (realtime processing where ms framerate processing counts).

Game design often also is multidisciplinary and requires knowledge of psychology, storytelling, music, and art.

Kids simply don't have the life experience, to put something together for this and have it turn out in a satisfying completed project.

Additionally, even when you are an expert, the experts don't play their own games most times. The vast majority of the fun and allure comes from the discovery of not knowing everything about the game and discovering it. This is why writing games for yourself is often doomed to failure.

Additionally, most games today have subtle manipulations and embedded addiction triggers. These aren't things they can just pick up and use. As an example of this, Call of Duty and Battlefield (FPS), have headshot audio triggers that associate through pavlovian conditioning headshots ingame with the dopamine hit sound cha-ching.

The ability to control addiction is in a part of the brain that doesn't usually develop fully until your 20s, and this stuff is in most modern games. There is a framework called the Octalysis Framework, it provides common methods to embed dark patterns in a way people don't perceive. It is based on some earlier work based in thought reform (torture), and later psychology experiments identifying key drivers to enable manipulation. This is extremely subtle stuff similar to what Pixar & Disney do in their movies (i.e. the handsome guy is always the villain, the preacher is always crazy...lot more).

Robert Cialdini wrote a book covering some of this precursor material. The book is called Influence, and it lays out all our natural perceptual blindspots, and how to exploit them. These are blindspots not even grown adults will notice most of the time without training.

I think you will be better served by starting them on something educationally constructive that is more suited for their age. If you are looking for something math related, Cosmic Calculator series has shortcuts that let you do math amazingly fast. Storytelling for writing authors may be good as well, or just focus on getting them to read for pleasure.

Descartes Rules of Method were particularly useful around that age as well as logic and reasoning (which public education will not teach them), since they are only just starting to be able to discern lies from truths, and that is a major developmental milestone.

Other activities might include Piano lessons, or art lessons.

The current gaming landscape is unhealthy, and can't be vetted by an 11-yo and even platforms designed to make this no-code easier, you have to worry about them suggesting and influencing in ways that will diminish them, or mislead, or creating interference and frustration, or something more directly harmful like TikTok and their recommendations to the Blackout Challenge (kids have literally died).

Some who don't have children might think this is overblown but there are no trusted platforms out there that will safeguard kids appropriately.

Google "Roblox kids scandal" and you'll see what I mean; and they've been recommended here in more than a few other comments.

Update: Sometimes I find it really surprising where others priorities are here on HN. You'd think protecting children would be paramount, but voting paints a very different picture, -3 for mentioning tiktok or the roblox scandal...