Soviet Republic Reborn 1950
Map from second game campaign, reworked for realistic start in 1950 and 0 initial money:
There are cities, but no highways, no mainline railroads, no underwater tunnels. Almost all roads are dirt. There is one abandoned mountain railway and two other short branches.
There is small island challenge: most uranium deposits are located on island.
I strongly recommend some mods with early vehicles (not included in this map), because there is no vanilla vehicles before 1960.