Go have a look at Excubitor on Steam http://store.steampowered.com/app/357030/
Excubitor is a sci-fi action tower defence game based in the Baphomet solar system; home to the vast ‘hyper-giant’, a star thousands of times larger than that of our own sun. You are a lone human pilot, responding to a distress call that leads to a struggle for survival; a battle against all odds that will test both your shooting and strategic skills to the limit. Armed to the teeth and set on a course of sheer destruction, a wave of drones is rushing towards Antares – the research vessel you are tasked with protecting. Players must build your defences in the best possible locations and load your Hammerhead defence craft with the deadliest weapons if you are to have any chance of survival.