I love the simplicity of the game, and yet how challenging it can be. But there is a small thing I think would improve the game. Most namely would be a "Key"

A toggleable key on the top/bottom/side of the screen to remind you of what the varous [#], {#}, and (#) brackets mean. If there is already such a thing in-game then I've not found it (at least not in the pause menu where it should reside). It shouldn't be a difficult thing for the devs to add though.

Feel free to suggest your own ideas in this thread also, and hopefully the devs will take notice. Perhaps a colour scheme modifier might be a nice touch too. I think a dark background option would be easier to see, and more "night-time" friendly for you nocturnal gamers out there