What you do, is ya make a shortcut to Blockland.
Rename it to "Blockland Editor".
Right click on the shortcut and click "Properties".
Where it says
C:\path\Blockland\Blockland.exe
change it to
C:\path\Blockland\Blockland.exe -mod editor
(Basically add -mod editor to the end with a space in front of it.)
Click ok and run it. It will be blockland, but with the gui and mission editor.