A real rarity. One of the first mods - potentially the first mod, in fact - that was released for the "Beta" version of Half-Life 2. It's author, Donald, released it on the HL-Inside forums in September of 2004, before Half-Life 2 was even released. It is not related in any way to the Half-Life storyline at all. There are four maps in this mod, each containing different enemies to fight. In the end, you will meet The Thing...

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