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https://love2d.org/ is pretty popular with people who are likely to be overwhelmed by 3D things and talk of engines and renderers. It is pitched as a beginner-friendly framework, but you can do a lot with it..

If they have a TI-83 or TI-84 graphic calculator, you can't beat Axe Parser! https://axe.eeems.ca/Documentation.pdf

It's as simple as the BASIC language that comes with the calculator, but it compiles to assembly so it's lightning fast. And you can write and build the entire game from your calculator. I spent hundreds of hours making games with Axe back in high school.

PICO-8 might be a fun starting point.

https://www.lexaloffle.com/pico-8.php

TIC-80 and LIKO-12 are pretty decent open source "clones"

https://tic.computer/

https://ramilego4game.itch.io/liko12

And then there's the BASIC engine:

https://basicengine.org/

CHIP-8 is really cool, too!