One of the best free games on the market. Youre playing a hacker with the goal to reach the top of the ladder by accumulating money, skills and reputation. Your tool is your homeserver on which you can create javascript scripts by actual coding. Your code is limited by you RAM since every function costs a specific amount of it. By upgrading your PC, servers and by hacking into corporate servers you gain more RAM which you can use to expand your code and run multiples of your hackcode to ultimatively extract money from the institutes.
The game further offers elements like factions, stockmarket, traveling and other tasks/minigames.

Bitburner has a very active reddit discord and github community, which helps immensely soaking up new approaches to optimize or restructure your code for maximum output. Whilst you dont necessarily have to know how to code, i want to point out that this game doesnt teach you concepts or javascript`s modules. It has a beginner tutorial, but after that youll have to use the javascript database documentation or sites like stackoverflow to learn about prompts/syntax/concepts. But the game offers a brilliant workspace you can use to experiment without consequences.

All in all one of the best free games on the market, and a great learning experience if you give yourself the time to adapt.