This is a video of game designer Dan "OtherDan" Emmons' analysis of the level design of Super Mario Bros World 1-1 and how perfect it is. WELL WHY DON'T YOU MARRY IT, DAN? I apologize, that was not very mature of me. I'm an adult, and I should act like one. But not if that means I can't drop my pants and underwear to my ankles at a public urinal, because I like to air my ass out. There's nothing grown up about establishing a swampy ecosystem in your pants.
Keep going for the video analysis.
Thanks to Crg, who agrees Altered Beast has a pretty solid first level too.