You would think it's just an ordinary MMORPG right? Wrong.
Made by Jagex Ltd, Runescape is an MMORPG, (Massively Multiplayer Online Role Playing Game) of which has some addictive effects on many people who created their 3D avatar, and started adventuring Tutorial Island.
This game consists solely of taking many real world skills along with Fantasy skills, and applying them in a 3D rendered world with thousands of other people. From Firemaking, Fishing, Woodcutting, etc. Runescape gives many players a feeling of striving for that next level just to PM their buddy, and say "In your face! I just hit 76 Fishing!" Then the new level granted unlocks new things to do, such as my previous example of 76 Fishing, which allows players to now fish Sharks, which can be used for profiting.
Skills aren't all of what makes Runescape a nerdy, cape wearing boy's wet dream. Combat is a huge part of Runescape as well. Combat bases your character's level which everyone can see. You then also have your common Combat Junkies as I like to call them, that think Combat is the only thing that matters.
Questing is also a great experience on Runescape as well, which is simply doing a certain task rated from easy to extremely difficult, and getting rewarded for doing so.
That's basically Runescape in a nutshell.
"Dude, want to go to mall? I can hook you up with my girlfriend's sexy friend."
"Nah man, I'm good. I almost have the Strength SkillCape on Runescape, and I can't stop now."