Custom Backgrounds will also be supported. Note that most Custom Backgrounds made by the SMF community are 16-bit themed, and Retro Edition is 8-bit themed, so most of them won't really work well. You can however make your own 8-bit looking backgrounds, and upload them to use them in your game! I am also planning on releasing an imgur album to upload more 8-bit Custom Backgrounds for Retro Edition when it's finished, and may add some more Custom Backgrounds every once in a while to the album. Of course, there will also be 9 in-game default backgrounds that are 8-bit themed that you could use. More info about how to import your own Custom Backgrounds into the game can be found on the help page.
-When the new version releases and if you have made a level in the old version, you can play it anytime by scrolling down on the page and select "Play old version".
-Levels made in the old version will not be compatible with the new version. The codes will work, but because most of the tilesets will change, the level will look weird.
(New) Super Mario Flash 2: Retro Edition will be launching this summer, at the end of August. Stay tuned for more info, I will post news here and there as I am developing the game on this page and on the forums!