War Thunder is Gaijin Entertainment's free-to-play military MMO, covering combined arms across aviation, armoured vehicles and naval craft from the 1930s through to modern jets. It's been running since 2012 and is cross-platform between PC, PlayStation and Xbox, so you can squad up with mates on other systems.

What's in it?

Three separate tech trees, air, ground and fleet, and you grind through nations: USA, Germany, USSR, Britain, Japan, Italy, France, Sweden, Israel and China. Historical battles, arcade modes and the more demanding sim mode for the hardcore crowd. Progression is slow unaided; premium vehicles and account time speed things up if you want to invest.

Decent entry point if you're eyeing up War Thunder, World of Tanks or DCS and don't want to commit cash upfront.