You could consider softening the assertion to something like the following.
Literature searches indicate that published academic research in video games, excluding applications to computer graphics, is confined mainly to the new millennium.
This replaces your assertion about actual academic research with an assertion about what literature searches reveal. If your field of study allows some informality in writing, then you could further soften the assertion to something like “Our literature searches . . .”, and now the claim is made only for literature searches that YOU have conducted.
I recommend omitting the filler phrases “but did not as a major part of research” and “maybe with a few minor exceptions”. Your previous remarks, and certainly my use of “confined mainly”, does not suggest the absence of minor exceptions. Besides, depending on what “minor exceptions” means, this could be said about pretty much anything, and thus these phrases add essentially nothing but extra words.
If you have access to ProQuest, which is likely if you have access to a U.S. university, then you can conduct full-text and title searches for “video games” (for title searches, use “TI(put search words here)”). Not all results of such a search will be available to you, but from among the theses that are available to you, there might be some which give historical overviews and/or literature searches that could be helpful, not only with relevant literature and research results but also with examples of the kinds of sentences you’re trying to write.