Unique but popular gameplay (it is the precursor to Apex Legends, but with mechs too), creative single-player campaign with fun characters, and the multiplayer has small armies of soldiers that turn what would be a straightforward match into a real battlefield with you as the super hero jumping over rooftops.
All this is to say, Titanfall is a game I remember because it was GOOD! My brother and I saw it, played it, and there was no doubt, it's one of the true greats of the FPS genre. The kind of thing that was a hidden gem upon release simply because it wasn't the best seller of its genre.