It's theoretically 4 years, but each year dev decides to "rework" the game, remove all current content, then slowly re-add some of it during the next year + make some new scenes, after which he does another "rework"... The game lost as much content as it gained over last few years.
If someone actually modded it to add all the scenes from previous reworks that got scrapped, it might end up being a decent game with a lot of content, but rn it really doesn't have much.
If you want to play it, your best bet is either to find the last version before the current rework, or wait until the current rework is at the end of its lifecycle, and then play it before devs scraps everything again.