First time I tried using the combination code on the locker, I flubbed it and then went to check the code again. But then lock pop up wouldn't go away, even when I pressed space or moved Pico to the next screen. Had to restart. Also, a little annoying that the ending screen didn't have an option to take you back to the title.
That said, nice choice of music and swell pixel art. The puzzles weren't too hard and the game progression was fine. I enjoyed it quite a bit, just hope you're not going to wait until next year to follow this game up.