It is fun, but there are some bugs. When your score got above quadruple digits it just sort of wraps back to single-digits, and this happens a lot once the multiplier racks up. I would suggest making the timer for the multiplier deplete faster if your multiplier is higher. I got up to level 99 as easy as I got to level 10, it just took a little more time.
Thanks for finding this bug and giving my game a try!
I didn't think anyone would get past quadruple digits or get a multiplier that high! You're definitely a lot better than me at this.
I fixed the score bug, and implemented your idea to have the multiplier deplete faster. I hope it's now more challenging for you.