Quite. I had a great Christmas break a couple years back going through all the missions. It has some edges to it but people have also implemented things like RISC-V in it so it's also quite complete. The game portion is enough for fun and exploration.

I got all the way to the final missions where you're writing your own assembly (that you created) to solve various programming puzzles. Only stopped because I got busy with something else and break was over. I def recommend it. Reminded me at the time of Code by Charles Petzold but applied.

(Last I checked the Author was rewriting much of it for performance reasons and to fix up a few gotchas that should be possible with circuits but aren't here - no idea if they still are but that was my understanding before)

The game has an alpha version appropriately named save_breaker that gets regular if not daily updates. Some of the later puzzles are completely different, the second architecture has been replaced with a more advanced one that includes pipelining, and some new puzzles are still in the works. The new assembler is much more modular and many of the components have changed shape, with some having been removed or combined. The author plans to release it as v1 when stable but who knows when that will be. Breaking changes still occur occasionally.

IMO, yes it is complete enough (note: I only went as far as the assembler challenges, I'd done enough assembler beforehand). But I did build a general purpose computer from NAND gates up.

Development still appears to be ongoing on Discord, which is quite active. I think the dev may have bitten off more than they could chew with their last patch promise: https://www.youtube.com/watch?v=38cKko7sViw

It's complete enough, yes. I played it up until the "main quest" was done (building a TC machine). It took approx. 20 hours and I loved it in a very similar way as the blog post author describes Nand2Tetris, so I'll have to look this one up too.

I bought it to revise my intro to computer engineering course before the exam and it worked pretty well for that. Didn't hit any bugs and it also was content complete as far as I could tell