in my original (now deleted) post, i made a complaint about the game being discounted on Steam, but not GOG.
even though i disapprove of biased treatment (sales, updates, etc) between game platforms, i don't assume that SURT is to blame. i know that they are a very small studio, and may not be receiving proper marketing and storefront support from TinyBuild (a company that i have had appreciation for, but seems less and less consistent as time goes on).
the only point that i want to leave on this post is- Rhythm Sprout is a very good game, and i hope that the developers gain some success from it. it would be really cool if they introduced some of the community-requested updates, but the experience they have already made shouldn't be overlooked.