2. Meeting Sovereign
When Shepard finally meets Sovereign - the creature that was pulling Saren's strings - they don't exactly exchange pleasantries. Instead, Sovereign decides to reveal its true motivations for his actions like a classic James Bond villain. Unlike them however, its plan isn't one giant cliché - it's smartly written stuff seemingly designed to make any sci-fi fan weak at the knees. It turns out that Reapers leave advanced technology (like the Mass Relays that made human space travel possible) around for organic species to discover so that their civilizations can progress. The Reapers then 'harvest' the species when they've reached their full potential. Hearing Sovereign explain in its incredibly deep, cold and intimidating voice that the only reasons humans have progressed is because the Reapers wanted them to is incredibly chilling. They've been around for billions of years and have been routinely wiping out civilizations casually like a pest controller - what hope do humans have against such a powerful enemy? Well, other species like the Protheans didn't have a Commander Shepard, and this was the moment you really felt the universe was going to revolve around you; a character that can change people's entire belief systems in a concisely worded sentence or two. Game on.