I'm a little late to the game on this one, but I just don't care. There's no way apart from magic-- or maybe magic mushrooms -- that Super Mario Bros should look this good running on an Atari 2600.
Atari Age is now selling Princess Rescue -- quite possibly only for however long it takes Nintendo's lawyers to get on the phone -- for $US30. For an actual physical cartridge.
I'm so horribly, horribly tempted, if only because this is one seriously impressive bit of coding
Princess Rescue a.k.a. Super Mario Bros. for the Atari 2600 [Dueling Analogs]