Sketchfab writes:
This month we challenge you to create a low poly game level. Once you’ve completed your model, upload it to Sketchfab and tag it #GameLevelChallenge.
To give or get feedback on entries, head over to the Forum! And to see all of the entries, check out the tag gallery.
I have a LONG history with Blender - I wrote some of the earliest Blender tutorials, worked for Not a Number and helped run the crowdfunding campaign that open sourced Blender (the first one on the internet!). I founded BlenderNation in 2006 and have been editing it every single day since then ;-) I also run the Blender Artists forum and I'm Head of Community at Sketchfab.
