Is this something where you're playing a game with another agent and you don't want him to predict what you'll do?

Yes, exactly. Kind of narrow, but I just find it really cool. And, lots of things decision makers have to do can be formulated as games with other agents.

I don't think those are opposite. They'll occur in tradeoffs, but only in the sense that any two things will. There's also speed vs cost, or speed vs documentation, etc.

I agree that they might not be "intrinsic", but if they're very commonly inversely correlated in situations we care about (which I think they are), then considering it as a trade-off can still be useful. See here for more.

"Risk vs Reward"

Thanks. I'll make this explicit next time. I like to have an upside connoted by both words of the trade-offs, which is why I didn't like risk vs reward.