Nothing official been said so far as I'm aware, but it used to be every unbalanced. On a successful ambush, you'd have, per player:”P 95: Surprised enemies no longer cannot take actions in the first Close Quarters Round. Instead, they now lose (1d) on all combat rolls in the first Close Quarters Round.”
What is the reason behind the change? Was the original rule unbalanced? Please explain why this rule was changed.Most combats shouldn't really last much more than three rounds, and you're getting at least halfway if not the whole combat in without there being an answering attack - three or four attacks on them. Thanks to the way the dice system works, later on in the game, it's fairly reliable to get the checks necessary to set up an ambush...it's unbalanced.
- An unopposed volley.
- Depending on the judgement of the LM, potentially a second unopposed volley.
- A full round unopposed.
- A Second full round.
- Finally, the adversaries can actually respond.
An ambush is still pretty powerful - unopposed volleys, and losing 1d is likely to make the opponents miss very often, but at least they have a shot (or alternatively, they'll spend Hate to get the 1d back, which is also a win for the players).
That's precisely the intent. Also note that the opponents lose (1d) on all combat rolls, which include Protection rolls. Yes, a Piercing Blow against an opponent caught off guard is now much more dangerous!
so does a player in melee have to remain engaged with an enemy or can he change engagement freely whenever he wants? (going against other enemies in melee or exchanging it with an ally for example)
No, they can't change engagement freely - at least, not in a single round. However, they can do so by "rotating" Rearward stance: a Player-hero goes to Rearward, disengaging from any opponent; close combat engagement is determined as normal, with any Player-hero remaining engaged with whichever opponent they were engaged with in the previous round, and possibly engaging the newly unengaged opponent (the one that was engaged with the Player-hero that went to Rearward); at the very start of the next round, a new Player-hero may go to Rearward, and the previous Player-hero may come back to close quarters and engage the same or different adversaries.
Seems a bit convoluted, but the general rule is actually very simple: the only way to change engagements (apart from killing the opponent or making them retreat) is using the Rearward stance (if possible).
Hope that helps!