Question: It seems pretty normal to see screenshots of MS Word, steps for "this is how you generate a template". I don't think Microsoft would object.

But I'm not sure about reprinting images from in-game scenes for specific games, like Diablo II. Do you need to obtain permission to include a screenshot of a game in your book?

Answer: 
There are four factors to determining Fair Use of copyrighted material that must be weighed in the balance:

* Purpose and character of use...better if not for profit; better if transforming in some way
* The nature of the work...factual is better, creative works less so
* The amount and substance of the work...less is better; uses that don't get at "the heart of the work" are better. There are no rules about percentages, etc, despite myths to the contrary.
* The effect of the use on market value...if it doesn't take away from real or potential profit, better

Depending on the nature of the book you are writing, you are probably quite safe using screenshots. You are likely writing something that will stimulate sales and that isn't going to reveal workings of the game that are protected.

Your publisher should have experience with this and probably has a policy for when they ask permission. Unfortunately, many people and organizations don't understand Fair Use and err too far on the side of caution, ceding rights they don't actually have to.

I teach about Fair Use regularly; you can find more information here: <http://iteachu.uaf.edu/develop-courses/constructing-a-course/copyright/>
Depends highly on the use.

If you were for example to make a story book and just use diablo screenshots as illustrations, that would (probably) not be considered fair use even if it is transformative. Neither would it be if you would just publish an outright art book by using the game assets as they are.

If you were making a book about the history of gaming in general, you do not need permissions to use screenshots. For this there is plenty of precedent and it is generally accepted practice, much the same that if you're making a documentary about 80's action movies you don't need permission to show the terminator 2 poster in context in the documentary.

However, it would be better for you if you took the screenshots yourself as that can put in another entity into the copyright chain. In other words you can't just copy the screenshots from a book containing all the nintendo games ever published and put them in your book about all the nintendo and sega games published.

Even including long stretches of video from a game even in a highly critical piece just badmouthing the game for 15 minutes is fair use(jim sterling vs. digital homicide, although that lawsuit wasn't just about the video I think they tried to claim copyright over it as well along the way).