Unlike Ray, I don't think having some (or even many) human-exclusive features is bad in and of itself. I consider Colonization to be more of an asymmetric game, unlike Civilization proper where everything is symmetric and all players start on a level field. Well, sort of. I just think even if the AI didn't know how to use or counter invisible units, having the whole native population go invisible (and that's the actual gameplay effect, no matter what the justification is) is bad immersion and annoying to play with. It would basically be like constant guerilla warfare. So if anything ever comes out of this, there needs to be considerable rethinking of how exactly you should go about it. Which is why I expect it to remain at the bottom of the todo list until at least 2025.