Not enmeshed in game development and have only done it very lightly: what takes a game like this 1.5 - 2 years to finish? Like at a minimum, it's art, sound, graphics, and programming. If they are re-using assets, that's one of them ~done. So what's taking them 2 years? My background is in SaaS type stuff and if I went to who hired me and said it would take 2 years to build out a non-cutting edge product I am pretty…
However, this is parallelizable: You can work on all 30 countries at once and ship when ready. You can work on taking and organizing notes in parallel. You can work on scaling in parallel. You can streamline UX in parallel while introducing tagging, or trees, or groups, or anything.
A game, and especially a narrative game, has an intrinsic linear component, the plot. You can work on a certain amount in parallel, sure: Once the rough shape of the plot is laid out, you can start working on assets, necessary engine features, sounds, dialog in parallel.
But you still have a strong need that a player or play tester has a good progression from act one to act two to act three, and a good progression from puzzle one to puzzle two to puzzle three. This takes a lot of very slow iteration.
This involves human testing by nature. You get a playtest every few months, if you have the money. You can easily throw more CI hardware to run your integration tests more often for more countries. Playtesters, especially those who don't know the game, are very, very limited.
Then you also want characters and settings to be consistent across the plot. If done well, this takes a lot of adjustments and refinement both back and forth. Sometimes the setting of Act three requires a character to have a certain trait, and that trait should be developed, so you now go back to Acts one and two to see if you can build up the character -- without knocking down the entire house of cards already in place.
And once you get to polish and atmosphere, it becomes even harder and more time consuming, because then you need new playtesters even more.
From a past job and working on some features, I spent a day or two presenting like 6-8 different options, and then spent half a day in different testing groups to figure out which procedural generation option "feels the best" for what the game designer wants. With a better spec, that could've been an hour. This made players more excited. Probably.