Did you play NG+ too? It's not quite finished but it's 90% there!
I saw information about NG+ but I thought it's only placeholder not a real thing :D
When you beat the first playthrough and get your score/time, there's an option to NG+!
I think your implication is that you stopped once the boss was dead? I think that's actually point to end the game. The bit afterwards doesn't add much.
nope, I got to the final "jump" section :D
Ah, well you made me realise that the post-boss area didn't really add much.