No downloads required. All that happens is that some text is on the screen and you need to choose w/e (Ex: You grab a soda. 1. Drink it 2. Drop it 3. Die. [except its way more funny :D]).
G4m3$ h33r (MyDoom.exe download required). (http://uncyclopedia.wikia.com/wiki/Game:Main_Page/Game_List)
Ther you go. Have fun (with MyDoom)!
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BTW I recommend the game Abyss. Its awesome.