I am suprised this is for very young kids. I couldnt make head nor tail of what you were to do from that video lol The game looks great for what it does. I think you should go the AppGameKit route and mobile it. It would suit the mobile platform better IMHO. As for the white grid I would defnintely lighten the white or make it smaller atleast. It is a bit off putting but nothing major.
I think you mentioned in the vid you would be looking for 10 dollars for this? Sorry but not a chance. I try and buy indie games as much as possible to support the community, even games I know I will never play but that is way to much for a game like this. I would think either 99c on the mobile or free with adds. That is until you make a name for yourself. Also I havent seen any branding. Who or what is your company? Do you have a website?
You are obvioulsy taking this serious which is great and something I would always support but you need to be more realistic for your very first game. I think Plants Vs Zombies (which is a huge game with lots of play time) was less than 10 when it was first released. It went up when it got popular but can be bought for cheap now. This game doesnt seem to have anywhere near the play time of PvZ. Also parents who want to shut there kids up with a game will more than likely look for something free first. So maybe free with adds on the mobile platforms would be the best option.
Just my 2c

Great job though and good luck with it!