艦隊これくしょん -艦これ-
Due to the high popularity of the game within Japan, game operators created larger numbers of servers in early 2013 to cope with the influx of players. During August 2013, the number of new players spiked by 100,000 people within one week, to a total of 600,000 people, with 350,000 daily active players. By September 2013, it was reported that there were more than 800,000 players regularly active. The total number of players broke 1,000,000 on 9 October 2013. As of April 2015, there were 3 million players. One commonly cited explanation behind the success of the game is that players aren't forced to spend money to play, unlike other popular Japanese online games; the free-to-play nature of "Kantai Collection" makes in-game purchases optional, and not a necessity. It is estimated that on average, "Kantai Collection" players spend less money on the game compared to the popular Japanese games "Puzzle &amp; Dragons", "The Idolmaster Cinderella Girls" and "Love Live! School Idol Festival".