Nintendo has Mario Maker on the way to let everyone build their very own Mario levels. In the meantime, you can take the busywork out of Mario level creation and just turn your computer screen into one with a single click.
Screentendo is a new desktop application made by Aaron Randall that allows you to easily create Mario levels using whatever is on your screen. After downloading it, you simply drag a selector over the part of the screen you want to use and then click inside to let the app do its thing.
The video above shows how this works using the Google logo. It doesn’t create a full level populated with enemies or a goal of any kind, but it does place bricks you can walk on and break.
Randall describes the app as “a proof-of-concept hack.” In other words, it has a number of limitations; beyond the time it takes to actually render a level, it “requires a reasonably distinct contrast in the underlying image for the block detection to work.” He also admits it doesn’t feel exactly like a Mario game, as he “didn’t set out to write a Super Mario Bros emulator, just something that would work ‘well enough.'”