A must-play game. You'll like it.
As you start out, your character is in a place called "Maple Island (and a sub area)" where you train on monsters and do quests until level 10. Then, you move onto the main island where a lot of the game is situated in (along with ossyria, and couple other islands), named Victoria Island. Then you get a job advancement out of 4 possible choices- Warrior, Magician, Thief, or Bowman. Later when you reach level 70 you can get your 3rd job advancement, and at lvl 120 the 4th job advancement (which isn't out in Mapleglobal yet).
As you can see, Maplestory is like your very own world. You can interact with people around the world, play mini-games, and even more. The community is extremely friendly, and the GMs (gamemasters) also hold exciting, fun, special events in which people can participate in. Overall, Maplestory is "da game to play" I find it entertaining for adults and children, and you should try it out. :)