Thank you very very much for this review!
My feeling about the game was as described: I felt I started very well, due to the fact that I ended up with lots and lots of influence towards the middle, but lost the game when trying to cut black stones and the ko fight started.
Thanks to your review, I find that we both made important mistakes and that my big starting advantage stemmed in fact from a huge mistake of my opponent: With a different response on the key move 31, White’s situation changes from good to terribly bad.
Also, I find that the game-losing ko and mistakes stemmed original from the strategical mistake of trying to cut the black tones too severely, ignoring the very dangerous aji of the P14 stone. As pointed out, White should try to cut only the G12 black stones, securing very large amounts of territory in the process. I am still VERY bad at estimating the scores and territory during the game 
I often find myself believing during the stone removal phase “Ok, I think the score is X” only to find I’m wrong by 50 points, which is obviously big enough to change the result.
On move 98 you write:
“There is nothing to be gained by sacrificing A. I don’t understand. It gives Black a really strong group and White still has to connect.”
Well, the explanation is actually very simple [Although the reasoning and strategy could be completely wrong]:
As stated before, I wanted to cut all of black stones with the sequence started at move 94. I even considered that letting those stones connect would now be game-losing. I was willing to start fighting for it, given white surrounding strenght. It is easy to read then that after M9 extends (as move 98) to save the stone, black ataris O11 and then white must respond N12, or else let black connect his stones, which we have already said is not the plan and we don’t want to and we consider would be game-losing. But then black O14 and then a net at M14 captures all of the white stones and the game would be over.
So that explains why 98 is played there. Given your comment, you clearly consider that black should capture M9 immediately instead of what was played, and white would then not be able to cut the inner black stones by playing O11 or similar, even though they would now be separated from the right side, because they have a lot of space.
Also, something I’ve not seen addressed but I would really like to know, as pointed out, is whether my score-estimation was justified or completely wrong, since my strategy was based on that very strongly, even choosing to resign, and choosing not to take the large corner black group, in a desperate try to kill the other even bigger group, since “I would lose anyway”.
To sum up these estimation-accuracy questions:
- Was I right to think I had a solid lead right after move 90, mainly due to my huge central mojo and solid lower side base?
- Was I right to think that after move 97, if black M11 stones lived, I would lose the game due to the mojo being mostly ruined with no hope to get enough compensation? (This is for example the reason I kept trying to cut them instead of letting them connect and settle for something else, justifying for example the “not undestandable” move 98)
- Was I right to think that, after black took the ko on move 117, simply capturing the black corner group, executing the threat, would leave me a losing position with not enough points (similar to 2)? [This belief is the reason I decided not to capture and instead go for the much more risky objective of killing the other larger black group, before resigning after failing to do so]
- Is there some advised way to practise global positional estimation? Things like “Black is 40 points ahead”. Even when only counting territories, as in the stone removal phase, I often find that my estimate can be like 50 stones off.
Lastly, thank you all very much once again, this review is very very very helpful!!
