Okay, so how would you win a mirror game?
It might be easy if you are playing as black since you are one move ahead, but how would you do it in general?
well, if you watch hikaru no go, you can do it by breaking symmetry (attaching to the center stone, or playing the center point)
So… to clarify, are you wondering how to win AGAINST someone who is mirroring your moves, or how to try and win BY mirror play?
I really don’t know so well myself, but there is a nice Sensei’s Library article about it
Perhaps he could be asking about both?
In the center mirror go works badly.
Let say your opponent occupy the tengen and mirror your moves. If you attach 2 times that makes him make an empty triangle. If you then connect your 2 attached stones, he get a stupid shape quadrat of 4 stones.
You can search by yourself how then to capture this ridiculous shape if your opponent just continue to mirror your moves.
There are a few difficulties with this method. first a contact on the tengen in itself is not really an optimal move (if your opponent breaks the mirror) as you start a favourable fight for him. It’s unfavorable because your opponent is already there, like it’s better to occupy an empty corner before approaching the already occupied.
Then if he still keep playing the mirror, you need to get better shape and result as his, if he decides to stop mirroring.
It’s not the only way. Another example is to see what happens when 2 Ladders are running to meet in the center (a bit more complicated).
Another more long term way is to make the center stone inefficient according to the other stones. It could be not too difficult in theory, but a tengen has quite some usefulness, like breaking a lot of Ladders (good for players who like fighting). It often become an extension from a wall or a stone part of a moyo, but in that case it may end not exactly where it should be (under or overconcentration)
In short, the player caught in the mirror has still a bit of difficult duty to use the center to break it, because if he delay, the player mirroring will keep the huge advantage to decide when he will take profit of a bad move of his opponent.
In that L19 topic there is a mirror game played by Kono Rin (9p) and a new young Japanese star Onishi Ryuhei (only 3p now)