The Mapcore game development community recently challenged designers to take the opening level from one of three games—Unreal Tournament, Counter-Strike 1.6, or Super Mario Bros.—and remake it in software of their choice. And that's how we got to see 1-1 as it would play in Unreal.
Level designer Sean Noonan, whose credits include a couple of Far Cry games, Watch Dogs, Star Citizen, and is currently working on Gears: Tactics, took on the challenge. You can follow his progress over the last month on Twitter. He translated the layout into 3D as a series of floating platforms in the sky, which gives it a very Lovely Island look, and since Mario doesn't carry a shotgun or a BFG 9000 Noonan gave him a gun that shoots plungers—thematically appropriate for a plumber.
All the Mario elements are there, goombas, mushrooms, coins, pipes, the lot. The end result is a tiny bit sacrilegious, while also being a worthy celebration of Nintendo's classic and a fun imagining of how Super Mario Bros. might play in an alternate universe.