Digital Combat Simulator World, or DCS World to its friends, is a free-to-play combat flight sim. The game is billed as a "deep, authentic, and realistic simulation designed also to offer a more relaxed gameplay to suit the user and his particular level of experience and training." You'll pilot iconic aircraft through simulations that cover multiple regions (Caucasus, the Black Sea, and others) and time periods (World War II, the Gulf War, and more) where you can engage in combat or simply hover above the action as your heart deems fit. You start with limited vehicles, regions, and time periods, all of which are purchased separately. The free-to-play portion of DCS World might still be enough for you to decide if you want to commit to the flight sim lifestyle, though, which can get expensive pretty quick as you buy more and more detailed peripherals.