Full ontopic this time (hijack failed
)
We had a battle yesterday where the "overwatch debate" situation came up.
We played it with a combination of the two side of the coin.
The overwatch fire is triggered, whenever the enemy formations movement passes the overwatch fire zone. Same way as aircraft touching the AA "bubble".
However the shooting itself is resolved at the end of the exact movement, so it may occur that the entire enemy formation goes behind cover / out of line of sight / out of range, still, if their movement touched the overwatch fire zone, they may receive their shots. (Also benefiting the cover modifiers, if there any.)
This way the zip-zapping from cover to cover is still useful and remain benefical, meanwhile the overwatch fire may
always be used as the rules basicly allow it.
I can only see game slowing issues, where there is a large gap among the overwatching unit's firing range. To punctually solve it, three markers may be required;
-One for showing the maximum range compared to the enemy movement path.
-One for showing the minimum range compared to the enemy movement path. (Actually it is for the opponent to adjust the probable firepower, and decide the risk according.)
-One for indicating how deep the enemy formation stepped into the fire zone.
After placing the marker, or indicating in any other method, the opponent finishes his movement.
Then the other player, looking at the markers (who may shot, are there any cover etc.) decides to use up the overwatch fire.