Back in the early 90's I remember downloading a graphics demo called, I think, "Unreal". This was on DOS on a standard PC and probably downloaded from a BBS.
It ran for several minutes at least and contained multiple segments of animations & music / sound effects.
Some segments were somewhat screen-saver like, others had more the appearance of a video game. But it was not interactive. Combinations of 2D and 3D rendering effects, etc.
At one point in the demo it showed the text "apparently this can be done", presumably referring to a particular effect.
From that text and other clues I got the impression this was some kind of portfolio of work on the part of the programmers who put it together. Maybe intended for a conference, convention, or competition. Seems like the work was pushing the limits of what was possible with A/V effects given the hardware of the day.
Periodically since then I've searched around for another copy of this, but no luck. Maybe the term "unreal" is too vague. Finding a video recording would definitely be fine, I wouldn't necessarily expect it to even run on a modern PC.
Note -- I think there is a video game called "Unreal" which AFAIK is unrelated to the software I have in mind.