I have to agree with the comment on the game page that a reason not to shoot might have been cool. Like, maybe shooting blocks that are a certain color would result in a whole area being deadly to the player. This deadly area would scroll down with the rest of the blocks, meaning the player would have to avoid it. That could of lent a bit of variety to the game.
Other than that, sound would have made a huge impact on things too. The sound of a projectile leaving the player. Different sounds for impacting different colored blocks - and that changing as they changed color.
But I appreciate what you did here with what I'm sure is minimal time on your hands. I might have to check out sfml sometime myself. So, thanks for introducing it to me!
If you could give my game a try and let me know what you thought, I'd really appreciate it!