A digital collectible card game (DCCG) or online collectible card game (OCCG) is a computer or video game that emulates collectible card games (CCG) and is typically played online or occasionally as a standalone video game. Many DCCGs are types of digital tabletop games and follow traditional card game-style rules, while some DCCGs use alternatives for cards and gameboards, such as icons, dice and avatars. Originally, DCCGs started out as replications of a CCG's physical counterpart, but many DCCGs have foregone a physical version and exclusively release as a video game, such as with Hearthstone. These games manage all the rules of a CCG, such as tracking the avatar's health, removing damaged creatures from the board, and shuffling decks when necessary. The games are managed on servers to maintain the player's library and any purchases of booster packs and additional cards through either in-game or real-world money. Some games, like Chaotic, Bella Sara, and MapleStory allow online players to enter a unique alpha-numeric code found on each physical card as to redeem the card in the online version or access other features. In other cases, primarily single player games based on the existing physical property have also been made, such as the Game Boy Color version of the Pokémon Trading Card Game and Magic: The Gathering – Duels of the Planeswalkers. Most DCCGs follow rules that exist for real-world implementations of CCGs, simply played out in the virtual space. However, some games like Hearthstone have gameplay elements that would be impractical or impossible to perform in a real-world game but is easily done within the digital game. For example, Hearthstone has a "Discover" keyword that lets players temporarily obtain cards from across the entire Hearthstone library for the duration of a match, even if they do not own that card yet. Prior to DCCGs, video games had used both card-based mechanics (such as Dragon Ball: Daimaō Fukkatsu in 1988) and collection-based mechanics (such as Megami Tensei (1987), Dragon Quest V (1992) and Pokémon (1996), all based on collecting monsters).