To me, this game offers teamwork and friendship that is hard to find in any other game. You don't get this team-based experience killing bosses with your entire clan playing any other MMO. This game is entirely unique to me, and the encounters I've had with different people have brought me to realize a lot of things about myself as a person.
Why does Celtic Heroes draw you in?
Here's what others have got to say about the game:

Celtic Heroes is a game for teamwork and friendship, trading with other people, examining them, it's a great way to bring people together.
For the most part, it is the people i meet in the game that provides me entertainment and fun and keeps me coming back.
I like the game its graphics are amazing and it's not hard to be a big part of the game as a player. You can propose ideas and the creators listen they interact with the public witch is a huge plus to me.
Its the people all the way.
I wanted to get a game, but my wife didn't want me to "waste" money. This was the best looking free mmo out there. It had no fee to download and no subscription charge. So since my wife consented I downloaded it and loved it. I wake up earlier than my family, especially on weekends. With Celtic Heroes I can grab the iPad and play it muted on the couch for a couple hours without waking anyone up. Also, my wife likes that it doesn't have scantily clad women around every corner or on the loading screens. I have since bought platinum since it's now the only videogame I play, but the original lack of a price tag is what allowed me to get it in the first place. It's a fun, easy interface with lots of different people to chat with, and plenty of stuff to kill.