I think the concept has some promise, but it doesn't quite come together here.
I think the game is hit a bit hard by the lack of sound and animation, which together make it fairly difficult to figure out exactly what's going on. The main goal also doesn't really get explained ingame, and the mechanic of bouncing the balls off the octopus doesn't end up feeling relevant, since you can still just toss the beach balls into the crabs yourself, which is much easier to aim and doesn't seem to penalize you in any way.
The hitboxes also feel inconsistent - you have to shoot *above* the crabs to kill them, since if you aim so the ball goes directly through the crab sprite, it'll just pass through them harmlessly.
There's also only 40 crabs. If you kill them all the game just... kind of stalls out? There's no end, you're just on an empty beach until you close the game.
I could see this going somewhere if the bounce mechanic was tuned a bit more, with the crabs only vulnerable to the ball once its been bounced or something; and with more enemy variety or at least more of the crabs spawning over time.