By unplayable I mean that it's at some point it turns into a chore and not a good feeling to progress through. So, at some point you stop since you've exhausted your will power to tolerate it. Not literally unplayable, since you can power through it, fair enough. It launches, there's pictures on the screen, some text, you know. That's not my criteria.
Your question has been answered by countless people before me, you can:
1. Search this thread with a word 'walkthrough' and read. It's 50 pages though.
2. Open reviews and CTRL+F word 'walkthrough' (or any low star reviews).
Over and all, the game literally ships with a walkthrough.html. It's meta information and should be disguised as in-game quest log to not destroy player's immersion. I like the content though, but the way you're supposed to interact with it is underdeveloped.