Probably using these tools:

• Unity 3D
• Pro tools 9 MP
• Sketch up
• Bfxr sound generator

Blog post with some tools I used for other LD project:

http://www.ludumdare.com/compo/2012/05/02/micro-world-toolbox/

I’d like to highlight GXSCC – Automatically converts a MIDI to 8-bit chiptune. Just drag and drop your MIDI to this window, then click Authoring to export it.

GXSCC

Good luck and have fun