Go to any Private, Ranked or split-screen match on the Estate map. Pick up a Sniper (or any telescopic sight weapon) class and when the game begins, go inside the estate (the largest house in the center of the area). Look in the rack under the LCD television in the main hall to find a Gamestation 5 console (reference to the PlayStation) with several games named "Italian Plumber Princess Rescue" (a reference to the Marioseries) and "Deer Hunter 17" (a reference: to the ridiculous quantity of Deer Hunter games). Also, go to the basement via the stairs in the kitchen and look at the posters in the wall around the pool table. There should be one with the name "Massey Effect" (a reference to Mass Effect) and in the same poster, there should be the description "Chaos Theory was just the beginning" (a reference to Splinter Cell: Chaos Theory, which story is considered the start of the subsequent Splinter Cell games' stories).