Anyway, I'd use the total concealment rules. First of all, the shooter must guess where the target is, and if he hits the target, there's still i 50% miss chance. Autofire would work best in this case I guess.
Oh, and what's RSV2?
As to the rules: yeah, that's what I've been doing so far myself. The 50% miss chance covers the massive recoil you get from blind-firing... Question is, do they lose a degree of cover when they blind-fire? Perhaps moving down a category of cover would be appropriate, for the round in which they blind-fire.
If you declare you are throwing a fireball/grenade at the square just past the corner of lets an alley you are not in, anyone that is around that blind corner (ie: in the alley you cant see) will be in the fireball/grenade Area Effect whether you see them or not.
Does the 50% miss work for area effects that you can see one end of the area but not the other? Like Autofire the first 10' of an alley you are around the corner from... you see one of the squares, how hard is it to guess that 5' north of that square (where you cant see) is the next sqaure.
Very important aspect was just mentioned & ignored.
If you declare you are throwing a fireball/grenade at the square just past the corner of lets an alley you are not in, anyone that is around that blind corner (ie: in the alley you cant see) will be in the fireball/grenade Area Effect whether you see them or not.
Does the 50% miss work for area effects that you can see one end of the area but not the other? Like Autofire the first 10' of an alley you are around the corner from... you see one of the squares, how hard is it to guess that 5' north of that square (where you cant see) is the next sqaure.
That's a good question.. all you can do is hope the GM keeps track of the exact location of the target. You target a square, and get a 50% chance of hitting the square you want.. otherwise scatter? With AoE weapons, still a good chance the target will fall in the radius. So target a square with full cover bonus to Defense, 50% miss chance, roll scatter on a miss. At least that's how I'd do it. Makes sense at all?
Well yes and know, this is were we need to expand the rules/house rules. We need to know does the PC know someone/thing is there if the PC does is PC hideing around the conor?
First there needs to be a hide check and if s/he succeds lets say DC10 then this PC is hidden. Unless they are standing in the doorway/alley way entrence.
Now lest say that s/he passed what know the PC has a rough estimate of where the enemy is so what I would say and this goes for shooting as well the PC needs to target the squire and if they can hit the squire then maybe the roll another check useing the % to see if they can get above or below however you run it. If you succed then yo hit with full damge. If you fail then maybe hail or no depending on evasion.
Now lets go back to the hide. Standing in a door/alley way you are in the open even peaking around the coroner in order to see everything. You would take at least 2-3 secounds to be able if trained that way to get a clear picture. To know how far away the enemy is and anything else thats there like cover. The PC wll need to make another hide/move sliently.
Now lets move to the dc its self you can increase or decrease dependng on what you feel is necicary. Now if your PC Passes maybe by 1-4/5 maybe the enemy is spoked and starts to move away or starts to talk faster or just see a shadow blur. Anymore or if you what to add more go for it.
Now if they fail we all know what happens. Enemy see them attacks/runs. No more explination needed.
Ok so lets say you pass your hide and are able to peek and stay hidden now how does your pc know what to do or are they just winging it? Lets say you make a knowledge tatics check DC15 know your PC gets a bounes to hit and maybe gets a +5% or 10% to the hit/miss check with the %.
This is all my idea on the fly I have never had a problem with this so here ya go.
More food for thought.
About AoE weapons. The only miss chance needed for this is for hitting the square (with a grenade, fireball, etc.). If you fail the d%, then use the scatter rules to determine where the stuff lands. That's it. A grenade is just as deadly if the thrower knows where the enemy is than if not (that is, if there's anybody near it). If anyone is within the Burst Radius of the nade (after rolling for possible scatter, etc.), then it's the normal rules for stuff like that. For autofire, I'd say that the firer simply misses, hits the ceiling, whatever, due to the hard time controlling the recoil. In my setting, however, I'd roll to see where the bullets end, to see if there are some poor innocent people who get ripped to bits instead. But that's me.
With a gun, you lean, fire, and pull back. There should be rules for popping around, firing, and popping back.
Otherwise people would just turn off the lights if they were in a room and claim concealment vs. the shrapnel from said grenade.
On that topic, what's the rule for leaning around a corner to fire a weapon? It doesn't come up in D&D. You have to actually occupy a square to fire from it (I think?), but I have to assume that that's because "firing" a weapon involves either loosing an arrow or using a magic ability, so there's a lot more stuff involved: knocking an arrow and handling a 5' bow, casting with somatic components, etc.
With a gun, you lean, fire, and pull back. There should be rules for popping around, firing, and popping back.
Use appropriate cover rules. I think there's an "peeping around a corner"-example under the cover rules descriptions.