In my continuing mission to work through everything I've accidentally bought from the humble bundle, I've got around to reus. Not a bad little game; I actually managed to get almost half the unlocks before my modding habit kicked in.

Surprisingly, there doesn't seem to be any mod tools yet, so I've made a simple tool to convert all the precompiled data to editable xml files and back. With it you can modify properties of minerals/plants/animals/aspects/challenges/etc, including adding new symbiosis's and rules. (Possibly adding new minerals etc too... I've not tried that, so no idea if it'll work.)

Download [url=http://timeslip.users.sourceforge.net:/temp/ReusEdit.7z]here[/url].
No installer; just copy the exe to the reus root directory and run.
Currently converts everything in the /Settings folder
Requires .NET 4.5
It also requires Microsoft.Xna.Framework.Content.Pipeline to be available. That's not a redistributable file, and the normal way to get it is installing XNA studio. That's a bit of a pain, and I tried to work around it by using monogame instead, but it generates the xnb files in a slightly different format, so although you can convert to XML and back, reus isn't able to read its own files once you're done. :(
It writes into the reus install directory, so if you've installed to program files it's going to run into difficulties.
- backups are saved in <installdir>/ReusEditBackups
- xml is saved in <installdir>/xml

Where two versions of a file exist, one ending in I18n, it's the I18n one that needs modifying. (The other one is left over from before the game was translated.)