Asset Credits (1.x)
Digi was responsible for all of the coding and writing, along with a lot of the UI art and sound effects, terrible as they may be. Other contributors (pay close attention if you plan on forking the project, as attribution is required by all of them):
Engine
Speo 1.x was constructed using RPG Maker 2003, an engine/editor combo from Enterbrain/Degica/Kadokawa Games.
Art
All of the monster art that appears in-battle was created by Monta.
Most of the character art and tilesets were sourced from the Loose Leaf/First Seed Material/Refmap project, a formerly well-known Japanese repository of assets for RPG Maker and game development in general. Their license is permissive with an attribution clause, and no active website for them currently exists.
The block 4 tileset, skill animations, and a handful of incidental graphics were created by Shironeji Ya, which I fondly translate as "White Screw ????".
Blarumyrran over at OpenGameArt created Speo's treasure chest graphics.
Music
100% Misoka (Pansound/PANICPUMPKIN).
Sound Effects
Quite a mixed bag.
Reinsamba is responsible for the goat bleat you hear in several places.
Blue frogs were given their voice by Dave Incamas.
gmajorr made the burp sound effect.
mich3d recorded a chicken laying an egg. Bold!
Thanks to j1987, your party's innards sound nice and crunchy.
Mark B. made a neat sewer ambience that isn't presently in the game, but is still included in the assets.