I started to develop Koala Dash a while ago, on pulp. As soon as the SDK was out I moved to develop it in Lua. This is my first serious Game, that I try to build. Hopefully I'll succeed!
In the actual state, there is a run length decoder that builds the level tile maps and placed the interactive entities, like boulders, enemies and collectibles. Boulder already have collision detection and that's it.
After jumping in, heads first, in a learning-by-doing kind of way, I now decided to consider the current progress as prototype. Now I'll continue, getting the data for all levels (ca. 120) together and ready. When that's done I will do art, music and maybe sfx, before coding the actual game from scratch.