In most PC games, the W and S keys move you forward and back. It's simple. But in MechWarrior Online, you're not controlling some puny human with a puny gun. You're controlling a massive, bipedal tank, and the controls have been tailored to reflect that.
So instead of simply moving forward, those keys increase/decrease the throttle, creating something of a learning curve, but ultimately a more realistic experience.
The devs here also detail systems that will allow you to customize your mechs, and some of the strategy involved in using different kits in different situations.
MechWarrior online is going to pit players head-to-head in these powerful machines some time this year. Is the mech combat genre in need of a revival? Tell us in the comments or on Twitter.