The Animus is the fictional device that lets people view genetic memories in Assassin's Creed.
In the series, the Animus is a machine that allows a user to access ancestral memories encoded in genetic material. The user does not literally travel through time; instead, the device reconstructs experiences from an ancestor's past and presents them as an interactive simulation.
Desmond Miles is the first major modern-day user shown in the series. Abstergo Industries originally uses the Animus to investigate Assassin ancestry and search for Pieces of Eden. Later games introduce newer Animus models and related systems, including the Helix entertainment platform.
Helix is therefore a common wrong answer, but it refers to a fictional consumer gaming system and also appears as a broader modern-day concept. Eagle Vision is an Assassin ability for perceiving people and clues, while the Leap of Faith is an acrobatic technique. Neither is the machine used to access genetic memories.