. . because:

Tools:
Programming: Action Script 3 with Flashdevelop
Graphics: probably Flash or hand drawn if there aren’t many graphics.
Sound/Music: Reaper, VSTHost, Guitar with Zoom G3X, midi Drums, myC64 organ, my voice or anything else that has a cool sound.

Or if I feel brave enough (and have a clear and simple enough idea):
I’d like to make a C64 game (but then I will have not so many possiblities for making music)