I had a good time with this :) The idea is good and every object's movement speed is quite nice. Cooldown timer for apples feels good too.
Some glitches when the snake is directly over the apple and has to keep flipping backwards to reach it, but that's fine. I like the music, and if you keep working on this then a couple of sound effects for hitting the darts would make it feel more awesome, and a sound for when the timer cooldown has finished would be helpful.
The initial few seconds works well how you announce and introduce each element. Use that style again if you end up ramping up the difficulty throughout. It currently feels fun for about 40 seconds and then maybe it'd be good to get faster or a second snake or some other complication to add more pressure.
Thanks for the fun time :)