A web search found that the PS/2 interface apparently survived for a while in gaming keyboards due to advantages I wasn't aware of - apparently PS/2 had slightl

A web search found that the PS/2 interface apparently survived for a while in gaming keyboards due to advantages I wasn't aware of - apparently PS/2 had slightly better latency and N-key rollover. Even those keyboard switched to USB eventually. The only recently made and currently available with backlight PS/2 keyboard I found is the "Zowie Celeritas II" gaming keyboard (the manufacturer's page says USB+PS2, the reviews say it ships with a usb TO ps2 adapter). However it's pretty expensive, and the red leds might not fit your taste.