I'm very glad to have found this game.
I work in healthcare, very long hours, and often in hectic circumstances. It's easy to get tired and stressed with challenging people - anger, yelling, random abuse. It's easy to become misanthropic and annoyed at people.
This game is amazingly calming. There's no people in it, no loud noises, no violence - only a cutely-rendered slice of environmental peace. There's a wonderful sense of solitude and quiet dignity in this game. It's challenging enough to keep you focused but not so much that you get frustrated with it.
Terra Nil is a terrific antidote to those stressful moments that we all get, from time to time. The concept is very creative; there should be more games about terraforming and environmental modification without a concern for growth, profit or power. It demonstrates the divergent scope of creativity that can be found in gaming.
Give it a try. Better yet, play it all the way through and send the developers a donation - creativity like this should be rewarded.
I hope you enjoy it as much as I did, and I hope you smile when you see the rain finally come down.