Website: http://www.maplestory.com/ (Choose your region)
Genre: Side-scrolling MMORPG
Cost: Free-to-play with a Cash Shop
Graphics: 2D

Graphics:
The graphics are nicely drawn, it has the best looking graphics of the 2D games that I've seen. The background moves as you walk, which make the game a little more realistic. As your level get higher, your skills look more awesome and your equipments look better.

Note: You can easily screw up your character by adding points on unnecessary skills. That's why you should check a guide before starting your character.

Pros (+):
-Even though it's tiresome to level up, it is fun and you make new friends
-Every class is unique and equal at the same time
-Party quests are fun but repetitive
-After many months of gameplay, I still haven't seen any hacker yet

Cons (-):
-Leveling up is tiresome (hours of grinding)
-No player vs. player system which means no competition between players
-A lot of scammers (can be avoided)