Congratulations.
Well, the file is in the main Atmosphir data directory (for the normal version, /<WHERE_YOU_INSTALLED_ATMO>/Atmosphir_Data/Atmosphir_Data/. For the dev version, it's just /<WHERE_YOU_INSTALLED_ATMO>/Atmosphir_Data/, because it doesn't have a launcher) I do remember it is required a commandline parameter (and I formatted my HD and can't remember it. Probably it is `offline`)
Some dev blocks who have proper block icons can be accessible via the arrow too because it's completed block.Means it can have moving block,falling block or interactive block
Edit Merged: Now I have created icons for dev objects/blocks.Please unzip them in atmosphir_data/images/
