SO I believe it was a nordic, maybe swedish detective movie from 2000-2015?. It was about many murders in a short time, that was actually a part of a game. The game was online and you had to register yourself there so you could play. So if you wanted to earn points in the game, you hade to kill someone.

I remember a scene where the detective waited at the metrostation undergrounds, suddenly the lights go out, he hides somewhere, and whene the lights comes back, everybody else was killed. The killers was a group of young people witch black suits and night goggles, and they hade knives or longer knives like katanas (can’t remember at all)

Then I remember it was a short like “DX” (it was like a smile or something, XD, :), X), X(, :(, XP cant really remember) at someones back in the online the game and it was like a huge clue at the movie.

At the online game were you kept track at your points it was like a maze where you met the other players.

Also the detective met two or one orphan boy or girl and she/he showed him the online game, cause the boy/girl was a part of the game.

I flummerly remember the ending scene where he walked out of a tunnel where the metrotracks were and he had everything solved out.

I really hope someone remember the title of this movie cause I saw this like a 10 year old and I really wanna watch it again!