XCOM 2 is on sale 60% off...

[Avilan the Grey]

Another issue is of course that the implication here is that only noobs play "lower difficulties". Although I have heard enough complaints that Overwatch was the Win All tactic (by seasoned players) on all difficulties (that's the main reason for the timed missions in X2 after all; to force players to stop using their favorite tactic).

And yes, Overwatch can work on already triggered enemies. That's after all the main defense for the strangler-squid thingies.

Edit: Not that I would try it, I don't care for achievements, but apparently there was a huge stink because you couldn't play with Tutorial if you wanted a zero death run since those two soldiers counted even though the screen said "Dead soldiers: 0" at the end.