The game is called Bitburner, and I have no affiliation with it. I just think it's cool.

You mostly play the game through a terminal, which allows you to create files and run JavaScript programs. It contains a JavaScript interpreter, but also allows you to run scripts natively. (I think this is done similarly to "bookmarklets.") Native scripts mainly have the drawback of being able to hang the game, so you have to be diligent about explicit sleeping in long loops.

Anyway, the game provides an API that allows you to take game actions (otherwise you write straight JavaScript, so you have its control flow and collections and the like), and as you get further in you get access to more APIs that let you automate more and more things.

It seems to me like a fun way of working on your programming skills.