A real life, stylized Mr. Hopp plush by Moonbit himself was available for a limited time.
An Esther plushie which is loosely based off the hidden collectable in the second and third game was also available for a limited time.
Descended Creator: While he's uncredited, Moonbit provides a few additional voices, most notably the Three Curses (with Mr. Hopp in particular) and The Entity in addition of being the creator of the series.