I had someone install a game port connected to a power inverter in my car. The game port ended up being a 2 prong outlet. I need to connect a 3 prong plug to it an have an simple adapter but I was wondering if the ground is really needed in this case and what would be the result if I didn't connect the ground?

What type of system are you attaching to the inverter?

The ground provides safety, stability, and protection.

Without a ground you may get a static build up causing failure of system (Usually easily resolved through a power drain). You risk electrifying any metal parts that are grounded during an electrical fault. A lot of metal cases are grounded in order to prevent shock should something inside go wrong. Most modern tech won't be harmed, but it may affect its functionality. I had an ungrounded computer system that would just quit working about once a month. I would just unplug it and drain the system and it worked again. It could be annoying sometimes though.

I don't know what a game port is?

Some systems use the ground to "commuicate" with other devices. It's also the place where the switching power supplies dump the electronic noise.

Thus, sometimes you need it and sometimes you don't.

Thanks for the answers guys I got what I was looking for.