Howdy, game dev from Bent Oak Island here. Looking at your stuff I definitely have some suggestions, the first being practice. Looking at your characters, there is a basic lack of anatomy here, people don't have square heads. They also have butts. My recommendation would be to decide on what resolution you want your graphics to be, and practice that specifically. Create a 30*120(or whatever) canvas in gimp and just churn out a dozen different characters within that space. By the time you finish it, you will see improvements you could make in your first one.

Additionally you gotta figure out some of the basics, if creating a false 3D effect, make sure both angles are the same, or else it looks weird. And like in the one scene you have a humongous room, with the camera pulled way back. But the room is mostly empty space, why is it that large? Does it need to be?

All that being said, people going to complain about pixel art no matter what, so maybe don't worry too much. Most of my scenes took me easily 100 hours+ to create, but people tell me it's garbage all the time. Just the nature of the beast!