I would contribute to:
- Finish the Tempest fund
- Create new seasonal map tiles (autumn & early spring with partial snow cover remaining) and new, smaller maps based on real-world locations. Also I think the terrains would look more realistic if the rocks were much less shiny.
- Revamp of the transportation system. More trains, marshaling yarsd in cities and ports, freighters which deliver supplies to ports, which are unloaded with cranes and loaded onto train cars. Trains run to large & medium field towns, truck convoys run from these towns to the towns at small airfields. Railroad tunnels through mountains, and realistic-looking trestle bridges which trains and trucks actually cross.