The entirety of Arcade Mode is an alternate universe DieselPunk version of WWII being fought with mercenaries.Planes fight for the "wrong" side, and you're expected to pay for your own planes, as well as any ammunition outside of bombs or standard belts.
- The Two Towns map would seem to support this. Two villages decide to go to war, but they wouldn't have a standing army. What do you do? Hire mercenaries!
- Further supported by the fact that many planes appear which were either never widely used or never used at all, such as the He-112 (which saw limited service in the Spanish Civil War but was out of service by WWII).