Let me revive this necrotopic...
I was looking for marsh terraforming modmod and found this topic full of ideas... but none of solutions. I tried to use (copy-paste) the code from post 24, but it did not worked for the last version RFC (BTS), not to mention caused saves crashed...
So, could anyone share a working modmod? Thanks
P.S. Personally, I would terraform march to grassland/tundra after windmills (says, 15 turns worker plus 10+1d20 turns city working it for a single shield (torf!)) and progressively faster (10 and 5 turns worker) after steam (2 shields - torf) and electricity (2 shields + 1 gold for torf power plant). And may be give a chance to flood it back...
P.P.S. Single food on tundra and forest replanting late game would be good as well...