Last time I did not quite finish because I spent too much time on the graphics. The game engine I used was OpenSLUDGE, which made the game creation part easy, so I felt the “substance” had to come from the writing and look. If I had to go back and do it again… I probably would end up doing the same though, and in LD24 I see myself making the same mistake – I know no other way. So my new plan is this: Ahem ahem…
First up, going for the Jam instead of the 48 hour compo. Secondly, I am getting help, but this is where it might get a bit interesting. I am co-owner of a Minecraft (& other) community at http://indiesquish.com/ and we have some talented builders on there. I also have been playing with the idea of using Minecraft as an oversized voxel editor, the results of which are shown in the pic below. Notice how the final output does not resemble the original build.
I convert the Minecraft world into a Wavefront object using a util called mcobj, and then render it in Blender. I use orthographic rendering because I like it, so nyah.
The idea is to have our whole community participating in the event, building buildings, landscapes, characters, spaceships, whatever is required from scratch. We’ll have several live streams going, and several time lapse recordings. It’ll be a grand experiment.

Here’s a standard flatworld with two villages:

So in summary:
– Game built using OpenSLUDGE engine.
– Voxel art drawn using Minecraft by a bucketload of excited kids (and a few big kids)
– Converted to mesh using mcobj
– Game graphics rendered in Blender
– Sound, will get back to ya. 😉
IMPORTANT: No assets from Minecraft end up in the final output. It’s just coloured cubes with no textures on them.