This website has listed a lot of their Steam Keys for ARMA 3 Lite. Usually you need to know someone who has bought the game to get your hands on one. It's basically the full game, apart from the editor or multiplayer, so a good way to try it out. Log In
I'm glad to hear that you managed to get one of the keys. I guess the rest are gone by now. Remember that this doesn't include the best parts - multiplayer and the level editor + levels from it. The full game is far better because of those.
