Size

Game Players per month Championship Prize pool Year game was released
League of Legends 27 million 2.2m 2009
StarCraft 3 million 1.6m 1998/2010
DOTA 2 1.2 million 18m 2010
CS:GO 800k 1.2m 2011

Work Cited:
wikipedia.com
dailydot.com
ign.com
ESPN.com
BBC.com
Leagueoflegends.com