This looks brilliant, but could use one clarification:
Am I required to look around constantly to ensure that I don't have line-of-sight to a martian?
Ie it's the line-of-sight that kills, not the seeing (unlike in Basilisk).
So, for example, playing with the Shard in instant-death mode, to play properly I should be constantly looking in the direction of the Shard to ensure that I can't see it.
Good point. I guess the answer is that no, you don't have to exhaustively check sightlines, but you shouldn't ever consciously avoid looking in the direction of a known tripod, as that's no fun.
I think there's a neat moment where you can see *most* of a tripod but it can't see you yet. They're more powerful than you but easier to see, so we can use that. It's like the mechanic in the old amiga game The Sentinel.
This would mean, for example, "only the very tip of an exposed crane boom counts".