Akilini was the predominant Matoran sport in Metru Nui in the years before the Great Cataclysm. In akilini, two to four teams, of between two and six Matoran players each, attempted to launch Kanoka disks through hoops defended by other teams. Players were designated either as "launchers," who carried Kanoka disk launchers and attempted to score points by shooting disks through opposing teams' hoops, or "defenders," who tried to block attempts by opposing launchers to score on their own teams' hoops. All players surfed on a Kanoka disk designated as a "transport disk" for the entirety of gameplay. Although the form of the playing field varied, at its most basic, akilini was played on a round field surrounded by posts on which the goal hoops were mounted. The field typically included obstacles or special features to make gameplay more interesting. All of these elements made Akilini a very fast-paced, physical, and dangerous sport.
The Coliseum hosted the citywide Akilini tournaments, which were held four times a year. In this sport, up to six teams of a dozen players each competed to see who could hurl the most Kanoka disks through hoops arrayed along the top of the arena. To make the game more challenging, the players surfed on disks over a constantly undulating floor and flew through retractable chutes positioned overhead. It was extremely fast-paced and dangerous. The winning team's disks were sent to Ta-Metru to be made into Kanohi masks.
The Coliseum was the site of the great akilini tournament, presided over by Turaga Dume himself.
Akilini was the official sport of Metru Nui, drawing hundreds of spectators for every match. If one wanted to play but could not get into the Coliseum, one could always play pick-up games played on improvised fields all over the city.
In akilini, teams of 3-6 Matoran competed to see who could throw more disks through the scoring hoops. Tournament matches were played on the constantly shifting and undulating field of the Coliseum, with hoops mounted along the top of the arena. A special set of chutes was lowered over the top of the Coliseum, which players were allowed to use in maneuvers. The essence of the game was speed and skill, and the physical nature of the sport led to a lot of fouls.
There were three tiers of akilini competition. The lowest rung featured play with power level 1-6 disks, the middle rung with level 7 disks, and the best players were allowed to compete with level 8 disks.
Teams were required by the rules to use only Kanoka disks made in their own metru in tournament play. In particular, non-Po-Matoran using Po-Metru disks was forbidden, as Po-Metru disks were widely considered to be the best in competition. Winning teams' disks were immediately transported to Ta-Metru to be turned into Kanohi masks. This was considered to be a great honor by Matoran athletes.
In the Coliseum arena, Matoran surfed on disks over the undulating floor while trying to launch their Kanoka into hoops mounted high on the walls.
Akilini was the major sport on Metru Nui. Akilini was said to have been created by a Matoran named Kodan, with the original version featuring a ball (see Kodan ball). Later, it evolved into a popular sport in which players launched Kanoka disks through hoops. Akilini was played on small fields throughout Metru Nui and in the Coliseum. The disks used by the winning team in a tournament would be sent to Ta-Metru to be turned into Kanohi masks.
At its most basic, akilini was played on a round field surrounded by posts upon which hoops were mounted. The field was not free of obstacles – in fact, the prevailing wisdom was the more, the better. Matoran would surf on Kanoka disks up and down structures, through chutes, and even through tunnels in the Archives, popping up only long enough to make a shot. "Street akilini" became so popular, and such a menace to pedestrians, that the Vahki eventually had to crack down on it.
A game was played among two to four teams of two to six Matoran each. Each team owned a set of goal hoops; teams scored points by launching disks cleanly through the hoops of any opposing team. Players were either launchers or defenders, and a team was required to have at least one of each. A team could have a maximum of two defenders and four launchers; a full team of six was therefore required to have them in exactly these numbers. Only launchers were allowed to score goals. Defenders were limited to taking shots to deflect opponents' disks, but players were prohibited from making physical contact with them. In order to replenish their supplies of disks, players needed to retrieve disks launched by their own team or disks from any team that had landed outside the playing field. The first team to reach 21 points was declared the winner.
Kodan was credited with the invention of the sport of Akilini. Numerous legends arose how Kodan first came up with the idea or how he first set up a crude akilini field in a Po-Metru canyon. However, over the years other metru insisted that the idea actually came from one of their Matoran, and in the resulting confusion, no one was really certain anymore who deserved the honor. After Kodan disappeared and was presumed dead, a monument was erected to him in Po-Metru giving him credit for the discovery.
- Akilini matches are played between more than one, but not more than four, teams.
- An akilini team consists of at least two, but not more than six, players.
- At least one player on each team must serve as a defender. A defender is forbidden to take shots and may only launch disks to deflect the shots of opponents. A maximum of two players may serve as defenders.
- At least one player on each team must be a launcher. If the team has more than two players, a maximum of four players may serve as launchers.
- One point is scored for every disk that passes cleanly through an opposing team's hoop. Disks that strike the hoop are not considered goals.
- Akilini tournament play ends when one team reaches 21 goals.
- Disks in play may be retrieved by any launcher or defender from the launching team but may not be recovered by opposing players.
- Disks that leave the playing field are considered to be open to all and may retrieved by players from any team.
- Players must keep at least one foot on their transport disks at all times. Transport disks may not be launched. Launching disks may not be used for transport.
- Players who go more than one bio outside of the field of play on any side will be considered out of bounds. However, players may go as far above or below the field of play as they wish and still be considered in bounds.
- Players may not make physical contact with a defender at any time.
- Players may make physical contact with launchers, but only after their disk has been launched. Striking, tackling, or otherwise making physical contact with a launcher in the process of making a shot is considered "roughing the launcher" and will cost the offending team one launching disk.