Well, definitely unconventional chord progressions.
Sounds pretty lackluster and weird, in a nice way. The part with the organ doesn't sound like it belongs in the song, though. Too "normal" for a somewhat chaotic piano melody. The drums are a bit lacking in my opinion. Doesn't have enough oompf. I like drums with oompf. It sounds like a level of Psychonauts (not as in the actual soundtrack, but from what vibe I feel from the game). I suggest you listen to Alfa Mist, especially his album Antiphon. It's got great jazz progressions and a calm feel, and it's very reminiscent of this track.
Thanks, and have fun!