Super Mario World Level Editor
"Super Mario bros was so 1985, give us a more updated scene creator!" Fine, let's blast forward to 1990/91 with Super Mario World! I have made it no secret that this is one of my favourite Mario games so it brings me great joy (and I'm sure a lot of lost time) to add this awesome Super Mario World Level editor/creator thing!
Once the game loads up you can select your SMW backdrop and then drag and drop (or right click and copy) items, scenery, baddies and even plumbers onto it to create your scene.
If you want to save your creation you will have to take a screen shot and save it into something like paint or some other image editing program.
Click the "Off" button to disable the music or click numbers to jam to different tunes whilst you edit.
Enjoy creating your own personalized Mario scene!
Check out the SMB1 level editor if you haven't already too!