CommanderZ wrote:1*1 didn't work?

Since you asked...
There's no towns, though, so the gameplay kind of sucks
Note that that's actually a 2x2 map, but two edges are void tiles.
Also, airport-sized maps, couldn't build any planes though, for some reason:
EDIT: Not that that stops you from having a 1x1 map with a single void tile... just disable the terrain gen bits that do modulo-by-zero:
The
ultimate in minimalist zen OpenTTD gameplay style.