Women and men had been barred from playing Hearthstone against each other during the Assembly 2014 gaming event in Finland, according to the terms of entry, which state, "The participation is open only to Finnish male players".
This is not the doing of the Assembly organisers, but the International e-Sports Federation, a global organisation based in South Korea. Every year since 2009, the IeSF has hosted a World Championship. At Assembly, the Hearthstone qualifier tournament in question is to find the player who will represent Finland in that championship, to be held in Baku, Azerbaijan in November.
Because the IeSF World Championship was divided by gender, this means that women were not allowed to compete in the Assembly qualifier either. "This is to avoid possible conflicts (e.g., a female player eliminating a male player during RO8) among other things," head administrator of the Assembly qualifier Markus Koskivirta told PC Gamer.
Which didn't really explain why women were barred from the World Championship, but don't worry: the IeSF indeed had a rationale.
"The decision to divide male and female competitions was made in accordance with international sports authorities, as part of our effort to promote e-Sports as a legitimate sports," the organisation explained.
This meant that there were titles for men and titles for women: four for men and two for women. Men were to compete in Dota 2, StarCraft II: Heart of the Swarm, Ultra Street Fighter IV and Hearthstone. Women get to play StarCraft II: Heart of the Swarm and Tekken Tag Tournament II.
After the organisation received massive backlash on social networks, as well as pressure from both Assembly and the Finnish e-Sports Federation, it revised and reversed its position, opening the male-only tournament to all comers -- but keeping the female-only tournament as is.
"The IeSF has listened to the gaming community and has carefully considered their opinions. Upon hearing these concerns, the IeSF convoked an emergency session of the IeSF Board to respond," the IeSF explained on its website.
"As a result, IeSF shall have two event categories: "Open for All" events and events that are reserved for women. The events which were initially set aside as the male division will now be open to all genders, and the events which were initially set as the female division will remain as they were.
"The IeSF Board addressed its reason for maintaining events for women, citing the importance of providing female gamers with ample opportunities to compete in e-Sports--currently a male-dominated industry. Female gamers make up half of the world's gaming population, but only a small percentage of e-Sports competitors are women. The IeSF's female-only competitions aim to bring more diversity to competitive play by improving the representation of women at these events. Without efforts to improve representation, e-Sports can't achieve true gender equality."