I like it! Simple concept, but surprisingly engaging! Reminds me of those "lock cracker" arcade games, mixed with a bit of roulette. Only real nitpick with the demo is that, since the bonus round is forced, losing points feels a bit mean... If there's going to be the chance to lose points, perhaps make the wheel optional? Or maybe just replace the minuses with 0's.
My best score so far is 1645. Great work!