TreffnonX wrote:
Overall my current takeaway is, that the turnout is heaviely dependent on the rules, and that what I describe is an actual problem with certain setups.
Your takeaway isn't correct.

What you describe is a problem with none of the rules that people use.
Every ruleset in wide use unanimously agrees that you cannot "gain" by playing a stone in the opponent's territory from the fact that they require 4 stones to capture it:
* Area scoring rules (Chinese, New Zealand, most computer-friendly rulesets) define your score to be the total spaces surrounded
or occupied by your stones, and captures count for nothing. Placing a stone deep in the opponent's territory and having them play to kill it affects nothing, since the entire region will still end up surrounded
or occupied by their stones and be scored all the same anyways.
* Many informal and casual Japanese/Korean rules (i.e. the way you'd actually play and resolve disputes in real life or in clubs with those rules), define your score to be the total spaces surrounded by your stones plus captures, and resolve disputes by *rewinding* back to the original position to score. If you play stones in the opponent's territory that cannot possibly live no matter what, the opponent just passes. Eventually you will run out of moves or have to pass yourself, so you pass too and the game ends. Then yes the opponent needs opponent to play 4 stones to capture your one stone, but once they play those stones and demonstrate that your one stone is dead, you always go back to the original position where the game first ended (the one after you both passed, but before they actually played those 4 extra stones) your one stone is declared dead as it stands, and you score from there.
* AGA rules achieve the same result as area scoring rules and allow you to physically play out disputes without having to rewind, while still allowing you to instead count stones plus captures, by through the previously described mechanism of pass stones. You can mathematically prove that the pass stones make the game equivalent to area scoring. So you can play the 4 stones to capture, and pass stones will make the result identical anyways.
* "Official" Japanese rules define things through an ambiguously-written and highly complicated system of hypothetical play which would be total waste of time for you to bother trying to understand, but also that when reasonably interpreted and fixed to best agree with the traditions and intentions of Japanese professionals, definitely do not have any such problem either.
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The rules differences only have far more subtle consequences that do not matter if you are a beginner, and none of them have any problems of the sort that you're worried about, don't worry about them. Pick what makes sense to you, and dive in and play and have fun, and ask experienced players for help when you come across a specific position that you don't understand.
