Heat Signature is an upcoming game from designer Tom Francis, since the release of his breakout game Gunpoint has allowed him to cast aside the shackles of game journalism to take up game development full time (thanks Rock, Paper, Shotgun). Tom's website is how to keep up with this, and there are already a couple of videos there explaining this is a stealth space game about temperature and a game about sneaking aboard randomly generated spaceships. He also notes that his main focus is still a prototype grappling hook game, even though that sounds less fleshed out than this. Here's word:

So you can jet around an infinite galaxy super fast, but your thrusters generate heat, and enemies can detect that from far away. The closer you want to get to them, the cooler you have to stay, and the more precise you have to be with your thrusters. And to take them out, you have to physically clamp onto their hull and shut down their systems.