Ritual

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Ritual Entertainment (formerly Hipnotic Interactive), has worked on two GoldSrc games, a Source game and several other games made on other engines (including the Quake Engine, Quake II Engine, and id Tech 3). These games are:

Quake Mission Pack No. 1: Scourge of Armagon

SiN

Counter-Strike (Xbox)

Condition Zero Deleted Scenes

SiN Episodes

Ritual developers also contributed a map to the Half-Life expansion pack, Half-Life: Opposing Force, produced by Gearbox Software. Ritual Entertainment was acquired by developer MumboJumbo on January 24, 2007, which was later defunct around late 2010s with it's website shutdown.
Following the acquisition, many of the developers have left to other companies such as id Software, Gearbox Software, Nerve Software, Escalation Studios, and the now-defunct Paradigm Entertainment.