and thats where there are two (well, 3) interpretations.

1: a broken formation on overwatch may not move, it is stuck there until it rallies
1b: a broken formation on overwatch may not move, it may still make a withdrawal, but cannot actually change its position
or 3: a formation on overwatch may not move, thus moving will break overwatch. if a formation is broken while on overwatch, if it makes a withdrawal move (ie: changes position) then it loses overwatch

also, as a note, formations on overwatch can still make another action in the same turn if they are somehow able to do so (ie: overwatch does not disallow this, the regular rules do, but again, its an indication that an overwatch action is not considered Ongoing any more than a sustain is)

now remember, a broken unit cannot shoot, so being on overwatch while broken has 2 possible benefits.
1: when you rally, you'll still be in overwatch. (this one is a bit silly, but no moreso than many others. i'd say its reasonable to let someone try to leave a broken formation motionless in the hopes of retaining OW for a second turn
and 2: while you're on overwatch, infantry get a cover save. (this one makes perfect sense to me. a broken squad can hunker down in cover, or it can flee into the open. if you're terrified and under artillery bombardment, which are you more likely to do?

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Sorry, but in that case neither can formations that have taken sustained fire action, which likewise "may not move". Formations taking a hold action. It doesn't say you can move again after the action is completed. IMO the rule is quite clearly supposed to be interpreted in the context of all the other actions, which allow you to make a number of moves between zero and two.

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Considering my point was that reading the rules to closely leads to weirdness, I think that only helps.

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Becoming broken removes Overwatch.

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Do troops on in the open on overwatch, who opt to remain on overwatch when they are assaulted, still get their 5+ cover saves?

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I would think so. They've not broken cover, so they would still get their defensive cover save.

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Could they countercharge? (Countercharging troops can normally claim cover as long as they're not Engaging.)

Counter-charging is not considered an action

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Counter charge isn't a move as per 1.7.x so wouldn't by the rules. Strange as that may seem.

I don't know about that. If they have the superior numbers and a Commisar, they may want to get the extra FF attacks to make sure they do not lose that bonus to kills through a clipping assault.

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So a unit in transports on overwatch can be charged, can counter charge 10cm, unload, battle, win, consolidate and remain on overwatch?

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~Laserwolf

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I don't know about the unloading, however the rest seems reasonable.

Remember units inside a transport cannot normally shoot so the case being given would be quite rare - unless they were skimmers(?).

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