Love the art style and sounds used- It reminds me of old gameboy color games.
The controls felt very responsive - I could quickly respond and precisely adjust my position when attempting to make a catch. The boulder catching was initially odd for the first attempts, as I wasn't certain whether I had to catch it with the end of the trebuchet.
A larger field of view might have helped in some scenarios. There were times where the boulder was thrown out of view, either off the top of the screen or out of your field of view side after you've caught the aforementioned highly thrown boulder boulder. This could result in getting struck from the boulder and occasionally felt like a cheap loss.
I did initially think that the caught boulders could be returned back to earn more points. Gradually adding more enemy trebuchets, in addition to being able to return fire could a potential mechanic to add further variance.
A short and simple game with retro-inspired graphics.