I'm not sure to understand how to predict enemmie's trajectory. Sometime they will go straight down, some othertime they will zigzag like crazy. This made the game quite random in the end, unless there's a mechanics I didn't see.
But I find the idea pretty neat still! It's like a tower defense, but instead of placing the turrets you place the targets. It's a cool concept. And even if the game aesthetic is minimalist, well, it does a pretty good job!