Super Koopa World is a critique of modern NPC character design through a Super Mario World hack. The central conceit involves the player taking control of a Koopa NPC with all that being a Koopa entails (which is not much).
The problem I’m critiquing is the lack of meaningful interaction with NPCs. Modern NPC design hasn’t progressed much past the era of SNES era design, with NPCs that are simply there to serve the player’s needs. In this case, the Koopa can only move left and right, trapped in its pipe prison until a player character (Mario) comes to either stomp on the Koopa or ignore it.