Hey, thanks for your comment.
This plugin is primarily a digital instrument with some synth capabilities that use the PCM as OSC.
If you have a method for translating guitar performance into MIDI data, then you could conceivably use your guitar to perform retro game music in Ableton using GuyEngine for sure. However, I can't officially confirm that'll be functional that way.
If you're looking to route GuyEngine audio out of your DAW, through pedals or amps, and back into your DAW, that's definitely possible.
There are already a lot of guitar players using GuyEngine V2 right now, so I imagine it would be totally usable for you as well. However just to be perfectly transparent, it wasn't built with that in mind - but that doesn't mean it wouldn't work - it's just never been tested properly.