This is an older version of True Creative. Instructions for installation are available both here and in a .txt file.
2)Make sure you have a program that can extract archives, such as Winrar or 7zip. I recommend 7zip.
3)Open your CastleMiner Z installation on Steam. You can do this by navigating to the file directory or by right clicking on CastleMiner Z in your steam library, hovering over "Manage" and clicking "Browse local files." This will take you directly to your installation of CastleMiner Z.
4)Make a backup of CastleMinerZ.exe. This is very easy to do. Simply rename your CastleMinerZ.exe file something like "CastleMinerZ BACKUP.exe"
5)Extract TrueCreative.7z into your CastleMinerZ folder.
If you followed those instructions, you're done. It's just a drag n drop installation replacing your existing CastleMinerZ.exe file. Enjoy!