Alex Pickering - code
OpenGameArt.org user Clint Bellanger - some art
OpenGameArt.org user ansimuzm, @ansimuz - a lot of art
Pascal Belisle - music & some sound effects
lospec.com user GrafxKid - color palette
game-icons.net user Lorc - some art
game-icons.net user Delapouite - some art

Software:
Amulet engine (amulet.xyz)
PeerJS (peerjs.com)
Moonscript (moonscript.org)
Bump.lua (https://github.com/kikito/bump.lua)