Heroes of the Storm revolves around online 5-versus-5 matches, operated through Blizzard's online gaming service Battle.net. Players can choose from three game modes, which include playing with/against computer-controlled heroes or other players. When players first start the game, they may play 5 heroes provided by the free hero rotation, a methodically selected list that changes weekly, but by using gold, the in-game source of wealth, or through microtransactions, they can gain permanent access to a hero. Two additional heroes are available to players who have reached level 15. As of July 2015, there are currently 39 heroes in the game divided into 4 separate roles. Of the currently released maps, 6 of the 8 have the standard 3 main lanes where players can fight, while the others have only two main lanes, but a separate objective-based area. Killing enemy/neutral units and the opposing side's heroes grants experience points, which are shared with the entire team. When a certain experience threshold is reached for a team, each hero on that team levels up, acquiring slightly amplified statuses and gaining a talent point upon reaching levels 1, 4, 7, 10, 13, 16, and 20. Talent points allow players to customize their hero's abilities and generally result in large increase in power, especially for levels 10 and 20. This leveling system emphasizes the importance of teamwork, since a player's action can affect the whole team. Players can also mount different creatures, such as horses or unicorns, to increase their movement speed, automatically unmounting when dealing/receiving damage or using an ability. Minions at neutral camps can be defeated to gain mercenaries that fight for the player. Each map has a different side-objective that will help either team deal significant damage to the other.