Oceania .v2
WW2 fighters being 2-3 times faster than WW1 fighters, 12-13 miles between airfields is the minimum to not have one side dominating the other with no breathing space to get in the air. I've taken this concept from NDisles and the three central small airfields that are 12 miles apart with the map room on the airfield as Hitech allowing such a configuration to be duplicated in the Melee arena. The caldera walls are 7k, the mountains on the central island on NDisles are 12k. The airfields are on a 700ft cliff over the water so LVTs cannot steal your base while you furball. That doesn't keep out M3 from one of the other airfields or c47. And tank furballers have a central area to play. It works out on NDisles, people defend the airfields from ground and air attacks while mixing it up in the center. Eventually I need to drop an airfield onto one of those white place holder squares along with GV spawns to the center and test the area.
Until you actually spawn out into your new terrain then fly and drive it, no one's including your own ideas are worth spit. I may have to change this thing another 5 or 6 times just to tune it for GV's like I had to with my previous terrain. That is why I'm only willing to use my ideas because I don't want to spend weeks rebuilding bad ideas once I put them in and actually spend those weeks testing them offline.
Death Bowl airfields 13 miles apart from 25,000ft

NDisles, Center island with airfields 12 miles apart from 13,000ft.

Oceania .v2.
