The "method" shouldn't be part of the "theme". You can add a certain method (no imports) as a condition for a contest, but it doesn't define a theme.
The "mood" shouldn't be part of the "theme" either. Admittedly, a theme like "gloomy" will probably result in 95% "dark" mooded pictures, but something like "Creation of the universe", which is a perfect theme, can still have different moods. And that's, IMO, what terraining contests are about: creating different moods and interesting combinations on one theme. That's what makes terraining contests interesting: different people creating totally different terrains on a very strict theme. It's mainly for that reason that I don't consider "blue" a theme.
A terraining contest should, IMO, have:
- A theme
- A method
The mood and the exact things you'll be showing should be up to the terrainer.
If I have to suggest some themes, here are some:
- The creation of the universe
- The end of the world (again, many people will think of apocalyptical stuff, but the mood is entirely up to you and the theme doesn't define the mood for you)
- Parallel worlds
- Immortality, timeless space
- Alternate history
- History kept secret
- War
- Birth
- First Contact
- The new world
- Religion
- Colonization (I'd love to see the huge differences in colonies you could create with warcraft models. Maybe a whole zeppelin fleet colonizing a mysterious air shard, maybe something Christophel Columbus like, etc.)
- Arcologies
- Cyberpunk technology in fantasy
With something like birth you can do a lot: birth of a child? Birth of an alliance, birth of a world, ...?
With something like blue, I'm totally clueless about the theme behind the word "blue".
It's making up something interesting that hasn't been done before out of a "cliche" theme like "The end of the world" that makes stuff interesting. The end of the world, it can be anything: Some "sorceress godess" turning a planet in the universe to a sheep, an apocalypse, maybe terraining those few minutes where a huge "black hole" opening a gateway to hell opens that sucks all evil inside while The heavens and the paradise is being created on earth, I don't know!