Yu-Gi-Oh! Online is an online PC game released in November 2005 by Konami, based on the Yu-Gi-Oh! Trading Card Game, players of the game can duel each other online. Later two versions of the game has been released, Yu-Gi-Oh! Online: Duel Evolution and Yu-Gi-Oh! Online 3: Duel Accelerator.
Players duel using cards, in the same way as in the Yu-Gi-Oh! Trading Card Game. Each player starts with a 40-60 card starter Deck. After that, players need to duel to get more cards. Whenever a single game (1 duel) is played, both players get 1 card from a card pack of their choice. Whenever a match game (2 or 3 duels, first to win twice wins) is played, both players get 3 cards from a card pack of their choice.
The game includes cards from OCG boosters up to and including Invader of Darkness, as well as a variety of OCG promos.
There are 30 player Levels, Levels 1 through 30. Once a player has played at least 36 duels, he or she can advance beyond Level 1.