Cute little game with a clever name.
Are the graphics original?
The hitboxes seem a bit unforgiving. Depending on the rotation of the player or the enemy, they may collide despite not visibly touching.
It took me a while to figure out how the sparks worked. I think the spark UI is a little subtle. Zero and one sparks look very similar. And when you get a spark, but kill an enemy with it in melee range, it can be hard to tell that you've just used (and possibly regained) a spark.
Another commenter mentioned not seeing their score increase when killing enemies at range with sparks. I also experienced this, but not on every page load. Sometimes it worked fine. On one run I killed probably 20 entities before realizing my score was still 1. So maybe some sort of system ordering bug there?