Glide wrappers are at a level where they can properly emulate how those games would look on a real Voodoo card and can be considered a viable alternative to the real cards. Since Glide was a proprietary interface, there were 3rd party efforts from early on to bring it to all 3D cards. If software does not straightforwardly access either glide.dll, glide2x.dll/ovl or glide3x.dll, it cannot be said to directly support the Glide API. This was again due to 3dfx being the dominant 3D solution at this time, and also a commonly known brand with PC gamers.
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It was also common for game developers to put 3dfx logos on their games' boxes, leading to misconceptions for a decent amount of games ostensibly supporting Glide which actually do not at all, or only provide a special MiniGL driver for 3dfx cards. The game also had Direct3D and OpenGL renderers, but Direct3D was well in its infancy back in the day and even the OpenGL renderer wasn't their best effort, therefore players with competitor cards had to wait for Epic's patches to improve the graphics, but in the end it would take fanmade patches to provide competitive renderers.
A notorious example for this is Unreal (1998), a game that was geared towards software rendering at first, but had a Glide renderer added during development as soon as it was clear that Voodoo would come out as the best 3D accelerator. 3dfx cards - namely their proprietary Glide API - can be considered one of the prime reasons to use vintage hardware today, because many early 3D games starting from 1996 had versions for at least some 3dfx cards, and in many cases these cards brought the superior image quality.