Cool and fun game! I will try to give some feedback:
When the game is not on fullscreen, you only see part of the screen. That's probably why some people did not see the timer.
The character could stick to the side of the platforms. Maybe you could add a physics material and set the friction to 0 to counteract this.
Also, to make the game feel more alive, you can add sound effects when certain things happen, for instance when the player jumps.
I really enjoyed playing your game, great job!