I think I have found the solution now and have had some ideas about levels and level data. It should be possible to upload the levels to a online server and share them with other users. Maybe have a rating and rank system for levels.
I have also been thinking about making a alien construction editor. You could have lots of parts to use to put together a new alien design. Parts could be animated, sized and placed around a center "body" part. It may be possible to render out the animation to say a 10- 20 frame animation arranged in a texture and use that for fast batched graphics rendering.