The much anticipated Dungeon Editor for Legend of Grimrock has now, officially, been released. If you’ve got it on Steam it should automatically be updating for you right now, while users who purchased it directly through Almost Human or through GOG.com can download a patch — read the full details here.
In the meantime if you’re keen to get modding ASAP, here’s a link to the official documentation. Almost Human also recommend Komag’s excellent video tutorials and their official modding forum. Already-created mods can be browsed at their Steam Workshop page or over on Grimrock Nexus.
To celebrate, you can now purchase Legend of Grimrock directly from the developers for just $7.50 (a steal if ever I heard it) for the next two days. You’ll get a Steam code as part of the bargain, so don’t despair.
Source: Grimrock Blog