I had quite some fun playing your game, good job! I think the basic premise is quite good, though I'd say the gameplay suffers a little bit when the priorities are conflicted. For example, should we be prioritising kill all people first and rolling down second? Should we roll down safely or should we go quick? This in my opinion what Sonic the Hedgehog games suffer the most, where you can't really have fun doing one thing but ignore the others entirely. I guess one way to fix it is to put the people in a good spot where if you roll correctly you should able to hit all / most of them, that way you got the enjoyment of a good rolling without making the player feel bad missing a bunch of them.
Anyway, enough said. I still think you did quite a good job making this game, so don't worry too much. Keep up the good work!