It's fun to screw around with for a bit, and make plots in your head, but it's a little overwhelming. Maybe add tabs, like "Sonic", "Items", etc, and when you click on the tab it'll show the sprites. Click it again and they'll go away. There also needs to be backgrounds, characters, items, and a way to delete sprites you don't want.
It's not bad for what it is but if you added more features then it would be a lot more entertaining. You should make a new one with the features I mentioned. Include all the characters and make sure it's organized, and add some extras like items and background props.