Portal was acclaimed as one of the most original games of 2007, despite criticisms for its short duration and limited story. It received praise for its originality, unique gameplay and dark story with a humorous series of dialogue. GLaDOS, voiced by Ellen McLain in the English-language version, received acclaim for her unique characterization, and the end credits song "Still Alive", written by Jonathan Coulton for the game, was praised for its original composition and humorous twist. Portal is often cited as one of the greatest video games ever made. Excluding Steam download sales, over four million copies of the game have been sold since its release, spawning official merchandise from Valve including plush Companion Cubes, as well as fan recreations of the cake and portal gun.
