Ravenfield is a first person shooter indie game with ragdoll physics where you and your blue allies need to destroy the opposing red team with using helicopters, cars, and guns.
There are quite a few options from graphics to gameplay but nothing for changing the main keyboard commands yet. It is surprisingly simple to play. Choose from a few guns and then you will spawn with your blue team and head out to destroy the red team. You can hop in the car and even drive a helicopter. Capture flags, kill the enemy and be the first to score 200 points to win.
One should keep in mind that this isn't a professional, polished game but instead was initially designed as an experiment with ragdoll physics and artificial intelligence but gained in popularity, so development continues casually. It is considered beta and in many places, it shows. It's not gory and it's probably never going to brag about its awesome high-resolution graphics but I think you will find it's the most fun you've had in a free FPS under 30 megabytes in some time.