Well not anymore that we have a no screen sharing rule in place, but before that yes it would be. It would have to be a virus you made and not something actively malicious in other ways. And you'd want to build in some detection that they're running Civ 6, as stealing their credit cards or spying on their private browsing would be unrelated to civ and crossing a real line. They could just as well do that to me. Unspoken rules also dictate you tell the truth when they ask "How did you know?". That would probably lead to another group meeting about no viruses. The disbelief of "you really did THAT?!" Is part of the fun. But there's no real harm done. Getting a friend to take a picture of your screen is conniving, but it's not harmful outside of the game world.
The hard part would be tricking them into installing something you've sent them, since we all live more than 500 miles from each other.
Interesting. I don’t think I’d enjoy that. It seems like it would give an advantage to people who would are most willing to push the boundaries of what exactly is considered fair play. I prefer a vigorous competition with obvious in/out of game boundaries. But, of course, that’s just me. I’m certainly not here to tell you and your friends not to enjoy things!
The hard part would be tricking them into installing something you've sent them, since we all live more than 500 miles from each other.