Yes, an intentional collision with a pre-existing stone is allowed. I used that in an example earlier here: Diplomatic Go - #6 by yebellz
I’m sure if I fully understood your specific capture counting scheme, since I think there are some details that would need to be ironed out. It’s a bit odd to share captures between multiple players, since it ends up double-counting stones. It also seems that two players could abuse this by feeding stones to each other to boost their scores over the other players, and they could do this at the end of the game, when no other moves are worthwhile.
Based on my rough understanding of your system, if all of the players share credit for the capture, isn’t it effectively like no one getting credit for the captures? Of course in the particular 5-eye case that I gave above, it has to happen in two stages, with only two of the players getting credit for the first part, and only 3 getting credit for the second part. However, one could imagine a simple 4 eye group that all 4 opponents cooperated to capture. If they all get credited for the same number of captures, that provides no additional incentive to capture.
However, I think the above issues are not even the biggest problem with trying to apply territory scoring. A much bigger issue is how to settle life and death disputes at the end of the game. Telling players to play on forces players to lose points (under territory scoring) by filling in territory to capture dead stones.
How do you propose to resolve this issue and deal with life/death disputes under a territory scoring system?
In summary, here are the flaws that I see with territory scoring for this type of game:
- Needs additional rules (and potential complexity) to determine who gets credit for each capture.
- Could possible be abused by players feeding stones to each other to arbitrarily inflate their scores (imagine this happening in a quid pro quo setup between two allies at the end of the game).
- Difficult to settle life and death disputes without distorting the score.