From the marketing to the name of the game itself, Titanfall pitches itself as a game defined by its use of giant combat mechs. And indeed, in your first few hours with the game, that'll be all you really pay attention to.
With good reason! They're visually impressive. The effect when they "fall" is amazing. They're a blast to control, and the way they're rationed is a stroke of genius, granting even the poorest player a temporary spell as a lumbering killing machine.
After a while, though, at least for me, the novelty started to wear off. I realised Titans make you a target, not a killer, and that while their means of availability are fresh, before too long they started to feel not too dissimilar from, say, driving a tank in Battlefield. You're trading power for visibility. Which is why it can be a good idea to never get inside them in the first place.
Were Titans the only thing going for this game, then, that might grow over time to be a pretty big problem. But Titans are just the window dressing. The real innovation - and enjoyment - to be found in Titanfall is in being on foot.
The sci-fi parkour powers you're granted by the game's future tech blow the doors off conventional first-person shooter controls. The viewpoint remains the same, but the way you control your character, and the way that character relates to the level around them, has more in common with a twitch platformer or a 3D action game than Call of Duty.
Spend enough time on Titanfall's maps and you start to notice that while the plazas and open fields are there for Titans to duke it out, everything else has been lovingly designed for the foot soldiers to move through, fly through and run all over.
There's expression to be had there, and that's what I find most enjoyable. Once you appreciate that at ground level the maps are designed on multiple tiers, you notice that what first looked like haphazard art asset placement is actually a grand enticement to experiment.
Think of each map not as a killing field, but as a Tony Hawk's stage. Every billboard, fuel dump and window exists not to dress up a level, but to encourage you to try and string together combos, only instead of getting a score at the end, you get a kill. Run, jump, wall-run, double-jump, straight into the window, kick a dude in the face.
This doesn't just change the number of buttons you press on your way to a statistic, though, it redefines the way you approach the game from the perspective. With wall-running and, more importantly, double-jumps at your disposal, you can do things that you've just never been able to do in a first-person shooter before.
Almost everything you've learned about shooters, from how you approach corners to how you traverse stairs, gets thrown out the window. Those rules, written for games in which you control a player stuck on two feet, just don't work in a game where you can leap between buildings, run along a canyon wall and cannon through windows. Climbing a staircase ends up being more Mario 64 than Modern Warfare 3.
I know, Mirror's Edge has perhaps more solid parkour controls, but that's a singleplayer experience. Brink tried something similar in the multiplayer domain, but your powers were limited to some basic, mortal moves. Halo's jetpacks (or even Tribes' aerial combat, or Unreal Tournament, or Planetside) come closest to what's being offered in Titanfall, but none of those are integrated into the player's core moveset (or level design) as well as they are in Respawn's game.
Most of the folks at Titanfall's development studio Respawn used to work at Infinity Ward. The last time they tried to roll the dice and reinvent first-person shooters was the original Modern Warfare, which (for better or worse) ended up setting the template for both singleplayer and multiplayer shooters for the next six years (and counting).
If Titanfall ends up being as popular and influential as Modern Warfare was, I hope the inevitable clones and copycats look past the obvious. Yeah, giant robots are cool, and look good in your trailers, but it's the foot soldier's player movement that's the real source of innovation in this game. If anything's going to influence shooters over the next few years, let it be that.