Star Wars: Imperial Winter is a free, multi-platform, real time strategy game using the open-source Spring RTS engine. Featuring over a hundred different units for the Galactic Empire and Rebel Alliance, spanning from The Phantom Menace to Return of the Jedi, SW:IW aims to not only contain the best gameplay of any Star Wars RTS, but the most diverse cast of units, including: Stormtroopers, TIE Fighters, X-Wings, stealthy Rebel Commandos, Bothan spies, Royal Guards, Wookiees, "reactivated" Battle Droids, repulsorlift tanks, walkers, and more! Gameplay features include asymmetrical balance, with the two factions playing very differently from each other; territory-based constant-income resource system allowing a fluid economy rather than paying upfront; realistic weapon physics, with every single projectile's path is realistically calculated, meaning your men can hide behind a hill from enemy laser fire but not from an artillery cannon, and many other features.
Cheap to put up, this turret is excellent for creating a 'danger zone' for attacking bombers and gunships, as well as making overflights by enemy interceptors and scouts very risky.
However, it does not make a 'no-fly' zone. In SWS, we do not think you should be able to put up a blanket of 'you cannot fly here' from the ground (unless you throw a lot of resources at it, which would be a waste). Ground-based anti-air measures are good at ensuring that the enemy cannot enter your airspace willynilly, especially with slower units like bombers and gunships. But if you really want to ensure the security of your base from airstrikes, you will need a defending wing of air-to-air fighters - and good radar coverage.