Free Software FPS Game Engine Based on Quake 3 for Windows, Linux, and macOS
That’s not a stereoscopic image (viewed by pointing one eye at each image – either by crossing your eyes or by doing the magic-eye thing with parallel eyes); that’s an anaglyph (red-and-blue glasses).
Stereoscopic images can be anaglyph, cross eyed, parallel eyed, and any other technique there may or may not be.
anaglyph is a subgroup
Cross-eyed is a subgroup
Stereoscopy is not as stereoscopy means any kind of 3d
However, ”naked-eye” is much better than anaglyph