Guys, I need your help once again. 
When I was introducing the game to my friends, something that I wasn't expecting happened: a character (a) hide behind another one (b) and the opponent (c) tried to attack (a) with a ranged weapon. The thing is (b) was invisible at the time. What happens in this case? Are any penalizations given to any of the creatures? Is there even a real line of sight or any coverage at all?
I tried but didn't find much help regarding this on the manual.
You cannot, in version 1.0 (Original edition) target an invisible creature. You can fire a line through a friendly creature to end up hitting the invisible one behind it (or in the way). This was one of the skills of 1.0... have a Helmed Horror (immune to lightning bolts) being fired upon with lightning bolts from a Dark Naga and then have the lightning bolt go through smoke to hit creatures hidden in there. A very effective tactic. As for ranger melee weapons - I've forgotten the rule for that
I think you can't attack.
In 1.0 you can't attack the invisible creature if I understood the rules right. But we weren't trying to attack the invisible creature. Just the one that took cover behind it.
Without the invisible creature in the way, the attacking creature would have a straight lign of sight to creature (a) and it would have made the attack. Since there was an invisible creature between them I rulled out the attack because I didn't knew what would happen.
And I know, me and OE. No matter. The rules don't seem to be explicit about it. If it helps I can addapt and use RE rulling about that.
I'm not 100% sure of the situation, but if there's an invisible creature in front of a target, the line will go through it, possibly doing damage (depending on saving throws etc.) and then will also hit the original target (as long as it is in range).
Piercing through one target to hit the other?
Really Ale? I know 2.0 is quite silly at times, but if ranged attacks go through invisible allies on the way (wounding them in the process) then that is just super silly.
LOL... ranged weapons... no... lines do - my bad!
For some reason I was thinking about lines... like lightning bolts...
No, is a ranged weapon (range 2 for instance) is deployed to attack a creature BEHIND an invisible creature I would rule that you get cover (+4 AC) for the defender.
You need to go back to your definitions.
From what you said it sounds like this.
C _ _ B A
Where C wants to attack creature A with a ranged attack and B is invisible, correct?
In 1.0, you could attack A, but there would be a -4 penalty to the attack due to cover. A is not invisible, even if he had hide, because hide does not work with creatures (see page 37 of the rulebook)
In 2.0, you only get the cover penalty if the
attack targets AC or Ref, if it targets Fort or Will, there is no cover penalty. The penalty is -2.
Kay, that's the exact situation.
Thanks for the enlightnement. (A) can be attacked afterall.