It’ll never be what most of us call a “simulation”, but if you’re after a bit of free fun in the virtual skies, Wargaming.net‘s World of Warplanes has now entered open beta.
Set in the period between 1930 and 1960, the aircraft technology trees cover German, Soviet, American and Japanese warplanes, in 15 v 15 teams, with a game lasting until a time limit runs out, one team achieves “superiority” or a team is completely wiped out. Being open beta, it’s still full of bugs, so don’t expect a 100% polished experience, but for a quick blast around the skies, you might find it good fun.
The link above will take you to the European site, but if there’s a cluster closer to your detected location, you should get a banner redirecting you to your local site.