That was a fun experience. I just completed the game in ~75 minutes with 777/777 coins but I only got the normal ending. Looks like I'm missing one gem. Is there a quick way to know in what zone to look or do I need to backtrack everywhere to find it? I'm pretty sure I'm only missing one. Regardless, it was a lot of fun and I enjoyed the challenge near the end. Thanks!
Edit: I've just found a full map online and I'm now 100% positive I got all gems. Also, they're all surrounded by coins so it's hard to get 777 coins and not all gems. Unless I'm really missing something? hahaha ! Anyway, it was great fun. Congrats for your game!
Edit 2: Oh... I think I've seen something on the map I was missing... don't want to write spoilers here for other thought...