League of Legends has a very strong playerbase worldwide compared to Valve's DOTA 2, which until recently was only accessible via invitation.
DOTA 2 was the most played PC title in the first quarter of 2013 according to multiple data sources compiled into a report by DFC Intelligence.
The company's PC Game Meter service established that usage of the top 20 PC games on the list increased year-on-year by 22% compared to the first quarter of 2012 and increased 8% compared to the last quarter of 2012.
The veracity of the top spot on the list has however been challenged by other outlets which point out rival MOBA title League of Legends far out performs DOTA 2 in terms of usage according to Xfire, one of the sources mentioned by DFC, and official statistics from the two games' developers.
Valve's DOTA 2 community hub shows approximately 250,000 concurrent players while Riot Games states that League of Legends sees more than 500,000 peak concurrent users every day.
GamesIndustry International reports that DFC has explained the discrepancy in its figures by pointing out that Asian markets represent a large chunk of League of Legends' player-base and that DFC Intelligence does not measure this, focusing instead on the US and Europe.
Regardless of which title truly holds the top spot, both MOBA titles are far ahead of World of Warcraft which sits at third place. DFC Analyst David Cole also name checks Guild Wars 2, Battlefield 3, Minecraft, World of Tanks and Counter-Strike as having driven players to the PC over 2012. He also states that Diablo 3 briefly contested DOTA 2 and League of Legends for size of player base shortly after its launch.
However, DFC Intelligence's PC Game Meter service does not necessarily tell us the most popular PC title at present as it only includes 'core' titles and excludes casual and browser-based games. There is still therefore a chance that both League of Legends and DOTA 2 are being thrashed by Solitaire.