Retro is always the in-thing, especially in games. You can’t not be cool with a genuine retro-reference somewhere in your game / gameplay.
Someone had requested that I adapt the Gonome from Half-Life 1 to VRChat. After extracting the in-game files, I was able to re-rig the Gonome model in Blender and export it to the VRChat SDK. Presently it is running the default animations of VRChat. Any classic attack / walk animations will have to be re-animated to the new rig (the in-game rig is from decades ago an not compatible, hence original animations are lost).
You will also have to go through the VRChat Unity3d tutorial for the proper uploading of the character. At the present time it appears there is no way to upload custom content except through the Unity3d interface they’ve provided.