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Developer(s) O2Media, Inc.
Publisher(s) South Korea Nowcom (Closed)
China 9you (Closed)
TaiwanJapan Gamania (Closed)
Indonesia e-Games (Closed)
Philippines IP E-Games (Closed)
Platform(s) Windows XP
Release date(s) February 21, 2005 as Open Beta, March 31, 2006 as Commercial Launching
Genre(s) Rhythm-matching
Mode(s) Single player, Multiplayer, Cooperative
Distribution Download (425 MB) or CD

O2Jam (Korean: 오투잼) is an online rhythm video game developed in South Korea by O2Media. There were agencies in many countries and regions, but as of 2012 it was only available in South Korea and was published by Nowcom. On 30 May 2012, Nowcom has shut down the O2JAM server.


Playing the game is divided between finding a room to play in, selecting a song, and playing a song. There are music-halls, technically servers, on which a user can play in. Some music-halls are named after the muses in Greek mythology.

There are 3 servers in the Korean version of O2Jam: Melpomin (Melpomin), Kalliope and Kleo (Clio).

There are also three servers: Kalliope, Kleo and Thalia. All three are free to use, although about half of the songs cost money to play. Each server works under song level restrictions. Before Thalia was introduced, in Kalliope, only songs level 15 and below could be played, while Kleo allowed all songs above level 13. As of 09/08/06, O2Jam has all three servers: Kalliope, which is now a level 1-13 song restriction, Thalia, a level 7-19 restriction, and Kleo, which remains the same.

There were six servers in O2Jam, all of which were free-to-play. These were Euta, Thalo, Kalliope, Melpomin, Kleo and Philix.


After choosing a server on which to play, the player (commonly called an O2Jammer in the O2Jam community) is presented with a list of "channels," each of which allows a maximum of 100 users at a time. Upon selecting a channel, the player is presented with a list of rooms. The player can either find a room in which to play manually, press the "Short Cut" button to take the user to a random available room, or press the "Create" button to allow the player to create a room of his own. The following are the types of rooms on O2Jam:

  • Single Rooms are rooms that only the creator can play in. These rooms are especially useful for practicing new or hard songs, since in a VS match the player may end up waiting awhile while the rest of the players finish the song. All of the same difficulty options and modifiers can be chosen in Single Mode. Until Level 10, playing a song in Single Mode can give a player EXP and mission credit, but after that the player must play in VS Rooms to level up further.
  • VS Rooms are where the multiplayer portion of the game is played. Up to 7 other players can join a versus room, and the person in control of the room (initially the creator) selects each song, difficulty, speed modifier and ring modifiers. A minimum of two total players in the room is required to play. The winner of the match is the one with the highest score.
  • Album Rooms are rooms in which one or more players can choose a song course and play against each other. Song courses are preset lists of songs with preset difficulties that are played immediately after each other without stop. The person in control of the room (initially the creator) selects each course, speed modifier and ring modifiers. Although there are many from which to choose, ranging in difficulty from very easy to very hard, this mode is not very popular. The overall score for the match is the sum of the scores for each song, and the winner is the player with the highest overall score.
  • Couple Rooms are rooms where two people in the same physical room or over the internet can play against each other. Player one controls the first four notes with the keys S, D, F, and Space. Player two controls the last three notes the keys 4, 5, and 6 on the numpad. No other players are allowed to join. Cooperation is needed to successfully clear a song.
  • Jam Rooms were a conceptual room type which were never successfully implemented into O2Jam. This kind of room involved each of the players playing the notes of one or more instruments in the song. Each player would hear what the other was playing, allowing them to collaboratively play the complete song, similar to how a band would play a song. However, due to connection issues, this room type was never implemented.

Selecting a song[edit]

Including all O2Jam versions, there are over 580 songs available for playing(~3.4GB in .ojn and .ojm files; over 1300 with unofficial songs included, 6.9GB). While some of them come included with the game's full installer, many of them require a separate download and e-points after installation. Unfortunately, the downloads of the songs are very slow, sometimes reaching 15 minutes on a cable modem. To fix this, all of the songs are available through a BitTorrent download.

The genres that the songs are part of run the gamut from piano pieces to techno versions of classical pieces to songs that are reminiscent of J-Pop, with an unusually large number of Christmas-themed songs. Most of the songs have 3 difficulty levels of play. The harder the difficulty, the more notes, drum beats, and other sounds need to be played by the player, as opposed to automatically being played in the background. On the hardest difficulty, many songs have a limited amount of music not being played by the user.

To be able to play a song in a VS Room, the song must either be free and each player have the song downloaded, or be paid for and downloaded by each player. To play in an Album Room, all songs in the album being played must have been downloaded before the album can be played.

A small optional step while selecting the song is selecting the background that all of the players will play on. This is mostly a cosmetic change, since all this does is determine what playing field the avatars will be standing on and what font the combo counter and note quality indicator (Cool/Good/etc.) will be in, as well as determining the visual effect that displays whenever a note is hit well. By default, the background is random.

Playing a song[edit]

Horizontal bars slide down a series of seven columns, each corresponding to a key on the keyboard. Just before the notes hit the bottom of the column, the player has to hit the key corresponding to that column. Each keypress emits a note, vocal, or other instrument that creates a full-sounding song. A correct hit is also rewarded with a small 3D visual effect that is determined by the background on which the players are playing.

The grading scale used by the game is, from most accurate press to least, Cool, Good, Bad, and Miss. Consecutive Cool and Good notes add both to the player's combo and to their Jam meter. When the Jam meter fills up (if you get 25 Cools, 50 Goods, or a combination all in one streak), a large number flashes in front of the player's avatar indicating their current Jam Combo. The goal of the player is to get both a high individual note combo as well as a high Jam Combo. Because the Jam meter fills up faster when a player hits a Cool instead of a Good, two players can both get a full combo (hitting every note as a Cool or Good) but still have a different Jam Combo.

 % of the note in the red bar Grade given.
80+ Cool
50-79 Good
49- Bad
Miss the red bar Miss

When the player gets fifteen Cools in a row, a blue pill appears in the pill meter, with a maximum of five pills. Each one of these pills will transform a Bad hit into a Cool, keeping the player's combo going.

After all of the players are done playing the song, their individual scores are ranked against each other, and all players are awarded Gems based on how well they performed.

One way players challenge themselves is by increasing or decreasing the speed at which the notes descend. The multipliers from the "base speed" are x0.5, x1, x1.5, x2, x2.5, x3, x4, x5, x6, and x8. These modifiers are often points of contention in VS Rooms, as many players try to play a song at the fastest speed possible, while others prefer to have the notes a bit slower. With many harder songs, x1 is used to increase the challenge, as the notes end up closer together, making it harder to read. Speeding up the notes does not affect the music at all, but instead spreads out the notes, making them (in non-extreme cases) easier to read in relation to each other, though the notes appear on screen for less time.

As of January 27, 2006, the x8 speed was replaced by the xR speed. This mode allocates a different speed to each note column when playing the song, making songs even more challenging, and difficult to memorize.

Currently the most difficult song in the official server is [H] Gaussian Blur, Lv.50


An O2Jam player can level up from level 0 up to level 100. Upon reaching level 100, the player's experience (EXP) continues to increase, but the level stays at 100. An O2Jam GM has a level of 999.


Every four levels, starting with level 4, a mission will be assigned to the O2Jam player. Unless a player completes the mission, the player's EXP and level will not increase.

However in the Korean version from Nowcom, the mission system is no longer available.


O2Jam has two methods of paying for items in game, one of which involves real-life money (e-Points) and the other of which is rewarded through playing the game (Gems).

  • e-Points are the universal currency on the O2Jam's host website, e-Games. The price is approximately $6.00 (USD) for 200 e-Points, with discounts when buying in bulk. Songs and avatar items can be purchased with e-Points, with the cost rarely going over 50 e-Points per song/item. The highest song cost is 50 e-points and the lowest is 10 e-points.
  • MCASH is the Chinese/Korean equivalent of e-Points.
  • Gems are awarded to players who play in either single rooms up to level 10 or in multiplayer rooms (VS or Album rooms). The better a player does on a song (the higher number of Cool and Good notes, max combo and Jam Combo) and the more difficult the song, the more Gems they receive.

As of September 9, 2006, bonuses have been added to the Gems on certain servers. Thalia gives +10% and Kleo now gives +20% to the Gem count per song. About half of the avatar items, and a small number of the pay-to-play songs are purchasable using this in-game currency. The highest song cost is 60,000 Gems and the lowest is 4,000 Gems.

Pay to play/free[edit]

The Korean O2Jam comes in both free and pay to play versions.

The pay to play version allows players a few extra options:

  • Avatars: Each player is represented with an avatar that they may customize with a wide variety of clothing, musical instruments, and other various accouterments. Paying members are allowed to buy additional avatar items with E-points (abbreviated to EP in-game), such as Skill Rings, which allow for challenging variations in usual game play (see below).
  • More Songs: Most of the new songs that are released for the game are only for the pay-to-play members. The vast majority of the songs are purchased with E-points, while a few of them are purchased with Gems. Buying a song only unlocks the user account's ability to play it.

Downloading the song files is separate from purchasing it, so many O2Jam players have the files for songs which that they cannot play.

  • Levelling Up: While on the Free server, players are able to gain EXP and therefore level up. The amount of EXP (experience) gained by players varies from song to song, depending on its difficulty and performance. The harder the song and the higher the score, the more EXP the player gains. As of September 9, 2006, bonuses have been added to the EXP given on certain servers. Thalia gives +5% and Kleo now gives +10% more EXP per song.

As of December 1, 2005, O2Jam has become free for all players. However, users are required to pay to play for about half of the songs if they wish to play them. Gaining EXP, buying avatar items and playing all of the free songs (of which there are currently 167, inclusive of 12 songs payable with gems) are freely available to all users. As of October 25, 2007, there are 149 pay-to-play songs on O2Jam, which results in a total of 316 songs (excluding previous removals) on that server.

Skill rings[edit]

Skill Rings allow for variations of the usual game play in different ways. Skill Rings must be activated by the room host and apply to all players in that room during the song period. There are three categories of Skill Rings: Arrange, Visibility and Power. Skill Rings may only be bought using e-Points, and last for a set number of uses before they disappear. Each Skill Ring has a different effect, as outlined below.

Arrange rings[edit]

  • Mirror Ring: This ring 'reflects' the notes required from one hand to the other. Uses: x10, x50
  • Random Ring: This ring randomly swaps the note columns for the entire song. For example, all notes which usually appear on the left-most column will appear in another random column, instead. Uses: x10, x50.
  • Panic Ring: This ring randomly swaps the note columns for a measure of notes. This is similar to the Random Ring, except the swap takes place every measure, instead of for the whole song. Uses: x10, x50

Visibility rings[edit]

  • Hidden Ring: This ring makes all notes disappear from view halfway down the playing area. This makes timing notes much more difficult. Uses: x10, x50
  • Sudden Ring: This ring makes all notes invisible for approximately the first half of the playing area. This shortens the viewing time for notes significantly. Uses: x10, x50
  • Dark Ring: This ring makes all notes invisible except for a small area in the middle of the play area. This is one of the most difficult rings to play with. Uses: x10, x50

Power ring/premium ring[edit]

The Power Ring was implemented on January 27, 2006 This ring can be used by the host and hackers alike to make all songs they have temporarily available to other players in the room, i.e. all pay-to-play songs which the host has purchased become available to players in the room. There are two conditions which must be met to allow this ring to work, however. (The feature has been implemented but the ring is currently not in sale) It was removed from the game due to massive amounts of hackers abusing the ring.

  • The host must have bought and downloaded the files (.ojn and .ojm) for the desired song
  • All players must have downloaded the song files (.ojn and .ojm) for the host's chosen song

O2jam Mobile[edit]


It is called O2Jam U.




External links[edit]