Indiegala offers Steam key downloads of Gunmetal for Windows for free when you join Indiegala's Steam community group and register your email. (You'll need to scroll down to get the key.) That's the lowest price we could find for this game by $10. It's a futuristic game where you take control of the transformable prototype combat vehicle known as the Havoc Suit.

You'll need to link your Steam and Indiegala accounts to activate the game.