Yeah, I drew and placed the trash in the last couple of hours, so it felt really rushed. It bothers me too that they aren't clearly visible.
I wasn't entirely sure what you meant by an 'incremental-style progression system,' but since there was no sense of progression, I decided to keep the run short. My original vision was a 3-5 minute loop with enemy drops (health, rockets) and increasing enemy spawns over time, but I ran out of time