Same as usual :)

• Haxe + Heaps engine (http://haxe.org)
• GameBase for the base code (https://github.com/deepnight/gameBase/ @ "advanced" branch)
• LDtk for level editing (https://ldtk.io)
• Aseprite for art

And side tools:

• LabChirp for the sounds,
• No idea for the music, maybe Bosca Ceoil?