There are Naval Bases, and nobody is a more committed advocate of railways in A&A than me.
However, I’ve been seduced by the game mechanics into thinking that maybe more is less and that we only need a few basic unit types. The extra power of defenders deals with trenches/fortifications/barbed wire, with tanks (if they function correctly) breaking the stalemate in favour of attacking.
If we add forts, then maybe we’d need heavy artillery to shell them; and so on and so forth.
I’d still like to see a few more aircraft types, mind.
Consider the present model as the early war reconnaissance type, fighting at 1-1. Successive types add greater firepower until you end up with a 4-4 fighter. Mainly this is restricted within air-to-air combat, so it doesn’t seriously imbalance the ground war. However surviving aircraft still get a single roll at their level vs ground. Don’t know yet if aircraft participate in naval battles.
Would like to find a source for WWI fighter models of the correct scale.
Also vaguely thinking about a light tank (I assume the game will feature the UK M series heavy tanks) alternative; cheaper to build but without the hit cancel ability. Attack! has some tanks that might just do for that.