An episodic video game is a video game of a shorter length that is commercially released as an installment to a continuous and larger series. Episodic games differ from conventional video games in that they often contain less content but are developed on a more frequent basis. Such a series may or may not have continuity, but will always share settings, characters, and/or themes. Episodic production in this manner has become increasingly popular among video game developers since the advent of low-cost digital distribution systems, which can immensely reduce their distribution overhead and make episodes financially viable. Alternatively, it can be used to describe the narrative of the game. Examples of episodic video games include most Telltale games, Alan Wake, the two DLC packs for Grand Theft Auto IV (included in Grand Theft Auto: Episodes from Liberty City), Life Is Strange and Star Trek Online.