3Dfx Game Wizard was the bomb :) I used it for years.
One funny thing about the Voodoo 2 card in the iMac was that it was a 3D card only. No 2D support at all. The onboard video still had to do all the 2D processing.
When you started a program that supported the Voodoo 2 card, the screen flashed off and on while the video feed switched from the onboard ATi card to the PCI Voodoo 2 card. During the installation of the PCI card, the CRT video cable was physically re-routed through the PCI card via a short extension cable that was included with the Voodoo 2 kit.
The Voodoo 2 card let me play Diablo II in 3Dfx/Glide mode (thousands of colors) on my iMac Bondi Rev A *much* better than my friend could manage on his iMac DV 400MHz. The ATi Rage Pro in the DV was absolutely no match for a 3Dfx (Voodoo 2 chipset) card. Nothing was until they added the GeForce cards with the LCD iMacs years later.
Later, I swapped the original daughter card (233MHz) out for a 333MHz from a 5 flavors iMac and I think the combo of the 3DFX + 333MHz processor gave me the best iMac (CRT) gaming platform there was.
If only there had been games... (sigh). Oh well!