Since the Vectrex was a console for small group of enthusiasts from the beginning on the only game controls that were produced are the original “joystickpad” and the LightPen. Missing 3rd party products make it difficult and expensive to replace broken joypads or buy another one for two player games.
Thanks later systems like Sega Genisis used 9-pin-subd for their gamepads aswell I only had to take apart one Genisis Gamepad and modify it slightly to make it compatible with the Vectrex.
On my gamepad I had to cut just 2 traces, drill one hole an add some wires. I used SMD Resistors since soldering SMD really saves time and space.
This is what the first prototype looked like (pretty ugly):
The main benifit besides the low cost of this gamepad is the faster reaction time you’ll have since genisis gamepads are digital and more egonomic than the big arcarde style Vectrex pads.
However one thing you cannot do is playing analog enabled games (only Hyperchase to my knowledge) since controls are only translated as logic on/off.
If you want to build a Gamepad on your own, here’s the shematic as .pdf file.
You will note that you’ll have to cut away some plastic of the standart Genisis Gamepad plugs since the vectrex gameports are very deep.