Many people make youtube history documentaries using recent closed source computer games to make the graphics. This involves playing the game as released, and using the gameplay graphics to explain the history. An example would be using a battle strategy game to explain the unit movements of a historical battle.
Do we know if this use is considered fair use? I assume that the game developers generally consider it to be free advertising, so it may never have come up in a courtroom.
(tl;dr: We don't know. It's probably okay legally if we take your example description at face value, and practically many companies openly or implicitly permit even less convincingly "fair use" videos, eliminating most legal concerns.)
US copyright law provides a fair use exception “for purposes such as criticism, comment, news reporting, teaching (including multiple copies for classroom use), scholarship, or research... .” So at first blush your described example, of using a battle strategy game to discuss and demonstrate real-world historical examples, would fall under a fair use exception for educational purposes. However, the court standard for determining if this claim to fair use is valid uses a four factor test that holistically weighs and considers the following factors:
Purpose and character of the use, including whether such use is of a commercial nature or is for nonprofit educational purposes.
Nature of the copyrighted work.
Amount and substantiality of the portion used in relation to the copyrighted work as a whole.
Effect of the use on the potential market for or value of the copyrighted work.
This analysis would be case specific. Perhaps the most immediate point of potential weakness in the claim to fair use would probably be the first point: e.g. is this channel actually trying to make profits (like a standard influencer or other YouTube celebrity typically would be), or actually operating as a non-profit educational venture. "History documentary" sure sounds like it fits the bill, but a court would examine the actual facts and behaviors to determine if this description holds water as concerns the claim to fair use.
An even murkier situation at present are "Let's Play" style videos, which are just people playing and talking about the game for its own sake. Creators of such videos claim this falls under the fair use exceptions as they are using it to create commentary on the game (and commentary is one of the listed reasons for a fair use exception). As such videos also use significant chunks of the game, however, there is the possibility they fail to qualify in part due to a consideration of the third part of the four factor test. The extent of usage would be weighed in part against the transformative nature and extent of the commentary added by the video's creator. To my knowledge no court has ruled on this issue. Some copyright holders will send DMCA requests to take down Let's Play style videos, but as a whole the gaming industry seems to have adopted the belief that allowing such videos to go unchallenged is in their best interests (either because of a "free advertising" belief, or because the outcome of a legal challenge seems too uncertain to justify the costs and PR challenges). Nintendo at first tried to stake a claim to money made from Let's Play videos of their properties, but later ceased and instead created an affiliate's program to split profits; Ubisoft openly permits usage for Let's Play videos, as long as the videos adhere to certain appropriateness guidelines; some games go so far as to have options to specifically disable things like licensed music so that streamers don't inadvertently fall prey to DMCA/copyright claims from other companies and artists; etc.
As such the legal uncertainties may essentially be mooted by company policies which already permit and/or enable the usage in question.
One of the major reasons for the fair use doctrine is that creation of certain kinds of commentary or other works would be impossible without using particular copyrighted material. If, for example, one were to try to discuss how Elvis Presley's voice changed between his early career and his later career, using recordings of Elvis Presley would be vastly better than using recordings of "Young Elvis" and "Old Elvis" impersonators. Even if the latter performers were so skilled that their recordings would be indistinguishable from the "real" Elvis, a career retrospective that used the latter recordings would actually be a comparison of the voices of the two impersonators, rather than the a comparison of recordings that captured Elvis's voice at different points in time. If the only recordings that can ever exist of Mr. Presley's singing are copyrighted, any examination of how his voice changes would unavoidably rely upon copyrighted recordings.
I don't think any such situation applies here. There are probably many games which could be used for the described purpose, and even if there happened to only be one, nothing would prevent anyone who was so included from producing other tools to perform such simulations. One could fairly argue that the reason for using the video game was to avoid having to spend money producing the footage via other means.
On the flip side, another aspect of fair use is the effect on market value. Although some forms of copyright infringement may enhance the market value of a work and yet still fail a "fair use" test, making a bona fide effort to enhance the market value of the work being used will offer protection in most cases. Video game footage that presents the game in a favorable light and avoids spoilers, while clearly crediting the title (and publisher, if needed for disambiguation) of the game would generally fall in that category.
If one were to offer a paid service producing battle recreation videos with the aid of the game, that may fall outside the bounds of "fair use" even if the created videos cited the source material. If you are producing the game footage for use in your own content, however, and you cite the source material, then I don't think the other "fair use" factors would be sufficiently negative to rule out the "no downside to market value" factor.
[Note: I am not a lawyer. I don't even play one on TV.]
