Thank you for the hint. Powder sources are already in the folder of possible future projects. Maybe after releasing Zelda Picross (that miss only sound) and Griffon legend, I could start it.
Poring Spelunky would be great, but coding the whole engine from scratch is a lot of work to do. I successfully imported Spelunky source on Enigma, but replacing the 386 toolchain with the devkit pro toolchain and porting all the needed libs for the 3ds, is time consuming too.
Witch Blast seems to be an easier project, the big work is porting SFML or at least mapping it's API to ctrulib calls. Let see if someone decide to start this project