Quick Quotes: Nicalis on 2D sprites in Cave Story 3D
"When we started on the project back in December, I really wanted to find a way to make 2D characters also work in 3D space. Being a Cave Story fan myself, I thought other fans would probably appreciate it too. Anyway, we've spent a lot of time testing and making sure it works right, but now we have 2D characters in the 3D game. This includes the main character, Curly, all the Mimiga-- literally every character and boss in the game as 2D sprites in a 3D world. What you won't see, due to the fact that it's a new engine and differences between the hardware, are the environments in 2D or the WiiWare sprites and art." - Tyrone Rodriguez, producer and music director on Cave Story 3D (via D'toid).