As of version v0.3, I made a incompatible change to the game settings class. As a result, when you start the rimworld there will be a RED ERROR message popping out.

The Solution is simple: Go to the mod settings page and find this mod, make any change (in fact your old settings might be messed up, you probably want to reassure the numbers there are what you want). Restart the game and it should have gone away.

This is my fault as I wasn't aware that C# code change could result in mod settings backward compatibility issue.

My sincere apology for the trouble.