The game concept I like the most is the Special Events system, which allows multiple tactical options that are almost equal in strength. In general I think the Youth Academy is the best feature in the game as it creates a close connection to your own players.
I like that Hattrick is a slow game. Here, I have time to think everything over. I also appreciate that Hattrick gives everybody the chance to be the best because you can't buy in-game advantages.
The first championship I won is one of my best Hattrick memories. I won the title in the 8th division by scoring a 4-3 winner in the 86th minute of the last league game. This put me tied with two other teams and I clinched the title on goal difference: 62-14 versus 61-14 and 54-11. I'll never forget the player who scored that goal, my Norwegian star striker Olav Aamot.
My best Hattrick memory was when the city where I lived (L'Aquila, Italy) was hit by an earthquake. I received a lot of support, a lot of help, a lot of love. It was a very hard time and Hattrick was there, with its community, with me. I will never forget that.
I would say the community is the strongest reason I have stayed in Hattrick for so long. The game too of course. After having trained my players and played in the French Division 2 for a while, I started focusing on training international players to help the Moroccan team. Today 80% of the defense of the Atlas Lions was trained by me!
What I like about the Hattrick community is that there are real people and you don't just compete against the computers. You play against each other, but you can also help each other in the forum and talk about everything.