Great work, and the adversarial aspect is an interesting twist.
One quick suggestion on the scoring.
Currently scoring favours quantity over quality so the best strategy is to just find the big empty areas rather than thoroughly clearing around bombs. If the score also factored in the adjacent bomb count for each revealed position it would make that a more viable strategy.
> Do not trust other people's flags though as they can be wrong - possibly intentionally.
Yes, this is intentional. I want to see how people start collaborating across very limited channels. Or how they start playing against each other :)