I am a 16k on tygem
Today I played against a 16k with an amazing record: 20 wins and 8 losses
It is amazing if you compare it with mine: 5 wins and 19 losses^^

He was really strong and somehow I won by only 3.5 points.
Since it was a close game I'm sure that I made many mistakes and it woul be great if someone can point them out for me.
I am Black, how strong do you think White actually is?

Just a very few comments. I am only little stronger than you, so take these advices with a grain of salt.

Move 11 at s16 seems small. There are larger moves e.g. at k4.

Move 55: Atari at s12, then make shape with p11

Move 163: Kill with s1

The strength of your opponent seems to be similar to yours. He made some obvious mistakes, e.g. he should have taken d3 at move 18. c3 allowed black to make more territory in the corner.

A few ideas:

Hi,

Just a couple comments.

Firstly I think your opponent is about your level. You both made loads of mistakes . I wonder if a little bit of fuseki study would help you? Don't go overboard though.

In my experience a high winning percentage says the player more about how hard the player is trying than how under rated they are. People playing normally make plenty of mistakes about their level so unless they're badly under rated those mistakes will cost them games. However people really trying to win will eliminate the careless mistakes which makes them almost unbeatable by a slightly weaker opponent.

Remember tygem promotes using winning percent - they probably really want a higher rank

Thanks everyone, I will continue to study and post another game sometime