The presentation is accurate and looks very professional.
Everything is consistent, the game really happens in a cartoony gold mine, which is funny, and the SFX are well chosen ; I like the sound of the wind when the coaster is falling. But I didn't hear the music... I think it's supposed to start when we click at the beginning. Am I having a bug ?
The gameplay is minimalist, only one button is necessary (it could even be played on a phone, I didn't try). This makes the game instantly accessible.
Your game is a fun one. I may come back every now and then to take a ride down the mine. ;)
The biggest problem is : you're absolutely not in the theme. There's nothing tiny here. I don't really see how to fix this. But maybe it's not the purpose of this submission.