Fallout 3 is an action role-playing game released by Bethesda Game Studios, and is the third major installment in the Fallout series. The game was released in North America on October 28, 2008, in Europe and Australia on October 30, 2008, in the United Kingdom and Ireland on October 31, 2008, and in Japan on December 4, 2008 for Microsoft Windows, PlayStation 3, and Xbox 360. Fallout 3 takes place in the year 2277, 36 years after the setting of Fallout 2 and 200 years after the nuclear apocalypse that devastated the game's world in a future where international conflicts culminated in a Sino-American war in the second half of the 21st century. The player character is an inhabitant of Vault 101, a survival shelter designed to protect up to 1000 humans from the nuclear fallout. When the player's character's father disappears under mysterious circumstances, the player is forced to escape from the Vault and journey into the ruins of Washington D.C. to track him down. Along the way the player is assisted by a number of human survivors and must battle myriad enemies that inhabit the area now known as the "Capital Wasteland". The game has an attribute and combat system typical of an action strategy game but also incorporates elements of survival horror games.
On several occasions Simon, Lewis, and Hannah have made reference to Fallout 3 and generally the Fallout series. Throughout Hannah's playthrough of Fallout: New Vegas the three made constant comparisons to the games predecessor, but admirably never belittled New Vegas under Fallout 3. In the first of the New Vegas playthrough videos Lewis explains how whenever they play a new game they compare it to Fallout 3, quoted saying, "In Fallout you can do this..." and "In Fallout you can't..."
Other references to Fallout are in "Fable 3 Co-Op Walkthrough Part 6", Simon gets stuck in the infamous tree glitch where your character attempts to jump down a hill and becomes stuck in a tree, and Simon recalls the character Harold from Fallout, who is an irradiated man who is technically half-tree. Harold appears in Fallout, Fallout 2 and in the quest "Oasis" in Fallout 3.
There is evidence to show what kind of character Simon and Lewis play after they disagree with Hannah's in-game methods of stealth and simple stubbornness to situations in the game. Hannah, on the other hand, takes the game light heartedly, which is shown greatly in her character creation sequence at the beginning, where she makes and gradually forms a bald bi-sexual woman by the name of 'Sunshine Kid'.
Simon and Lewis made a very basic video review (in the good old Yogscast way) of Fallout 3 which consisted of Simon playing for 10 minutes with Lewis doing most of the talking. You can find the video here.