Maybe I'm missing something, but the game tends to ignore my keystrokes in intense situations. It happens especially in close quarters when I'm trying to melee swing, or when I'm trying to switch to my weapon's under-slung armament. Not being able to melee swing against a rampaging Ceph is lethal, and without quick-saves it is a game-breaker. Some functions (usually melee, weapon switching, jumping, crouching) are hampered, while others always work (firing and armor switches). I also can't switch weapons when reloading, and while that may be a design choice, it is a terrible one.