The pixel art/animation looks really good. I love the concept too of amassing a slime army, however, the actual added power of extra slimes diminished because their projectiles could be destroyed by running into the other slimes. So even with 15 slimes, only a few projectiles would end up hitting the target. I still think it's a really cool game though! Oh yeah, and I think increasing the movement speed would have made it more fun as well.