Free-to-play FPS mecha shooter Hawken from Adhesive Games will soon be moving its heavy-metal action to Steam. Players have been alerted of the transition via email and this move will see the game only playable via Steam.
Existing players will receive their early access code for the game via email which they can activate via Steam. A Steam account is mandatory. Registration on the Hawken site will be disabled.
You can read more in the official Steam Transition guide.
This can prove largely beneficial to Hawken as it will be exposed to the extremely large Steam userbase.