First off, I really like this forum editor.
MagicaVoxel is my software of choice right now. Might play around with finishing stuff off in blender if I can learn it enough in time to add something to my work.
Contests are a great reason to play around with art. I have a few ideas in my head, not sure how many will make it to the entry stage but it's fun finding out which ones will actually take shape. I love @elbriga 's dragon castle example and thought it would be cool to start with a massive monster type scene. I'm building all the components of the scene right now and will arrange them later.