Expansion pack
An expansion pack is an addition to an existing computer game. These add-ons mostly add new game areas and/or an extended storyline to a complete and already released game. The changes these packs do to the original game differ. Expansion packs are developed by professional game companies and are not free, which is the difference to game mods.
An example of an expansion pack is Blue Shift for Half-Life which lets the player see the happenings during the original game through the eyes of a member of the security personnel rather than the eyes of a scientist as in the original Half-Life game.
The price of an expansion pack is usually much less than that of the original game. As additions, most expansion packs require the original game in order to play. If a game has had older expansions, new expansion packs often feature all or some of the game's previous expansions. Games with many expansions sometimes begin selling the original game with the oldest expansions, such as The Sims Mega Deluxe (the original game with The Sims Livin Large, The Sims House Party, and The Sims Hot Date). These collections make the game more accessible to new players, but publishers are careful to not make them compete with their own expansions that are still selling.
The Expansion Pak is a RAM add-on for the Nintendo 64 console.
