Heroes of Pico's School I finally beat this without a walkthrough! Some of the best puzzles I played in a while, every mechanic and character had ramifications you needed to consider, combine and use to their fullest.
I also adore the soundtrack, "Ladies and Gentlemen" was especially great background while studying a puzzle.
I love the presentation too, the little sounds and animations for moving around really tie it together.
I do have a minor gripe with the menus, although this could just be personal taste. In RPG Maker 'Z' is to select and 'X' goes back, so having it reversed felt weird. I did have an odd amount of fun holding back on the credits screen though. Going for as long as possible without returning to the main menu sounded like revving a motorbike.