Popular Video Game Clones?

So occasionally a game is brought to my attention that is suspiciously identical to other more popular mainstream games.

Dota, League, HoN

WoW, Runes of Magic, Runescape 3

One format that I haven't seen recently would be a RuneScape clone.

Can you guys suggest a game that follows a similar format to RuneScape?

Also discuss any other games that are compete ripoffs of mainstream games.