I want to run a game on my NES mini but I don’t know how. Or if I can. Please reply showing how I can do it or if I can.

You turn the NES mini on, pick a game, then play it fast.

^ after that, you point a webcam at the TV (assuming it will let you capture it in watchable quality, preferably with audible audio) or you buy an HDMI capture card to capture the gameplay.

I have a SNES mini classic, figure it will be similar in set up to your NES. Anyway. My SNES has a HDMI output, so I plugged it into my Xbox One HDMI input and can play it through the TV app. From there I think I can record via Twitch. Depending on what you have with HDMI input, something similar might work for you

Xbox one has an hdmi input? Gonna keep that in mind.

Yup. Real handy these days with more and more devices wanting to use my TV's limited HDMI ports. XBox wanted to be the media device and have your TV run through it then tell kinect to play your shows or something. Works well for a second console though.

That’s actually an interesting idea. I didn’t know it had an HDMI input either

Yeah, I've having problems with the gtx 760 at the moment; could be pretty useful considering an Xbox One used is about the same price as HDMI capture card. I can route different computers to it and stream from there, and worry less about the graphics card crashing OBS in the middle of a stream.

I guess it would really come down to if it had a way of some sort of basic overlay or timer, or something.