What rev did wrong and how to fix it (maybe).

[Captain_Bravo]

Hmm... No, you're right, there should be a way to tell... What if we make it so implanting someone with a multi-use implanter gives them a special birthmark that's unique to that implanter for that round? So, if someone is a mindslave and they examine someone else, they could notice "This person has a mole in the shape of a butt on his face." "This person has a clown-shaped birthmark". Non-implantees can't notice either, so, spymasters or security won't have a dead giveaway.

And, if you wanted to bring back Rev, just make a special spymaster round where all the spymasters have the objectives "All heads must be eliminated" and "All fellow spies must be alive at the end of the round" and give spymasters the ability to purchase pinpointers.