Update (12/24/09): A few minor bugs fixed and another known bug added to the Readme.
"A Strange Mission" is a hack that I've been working on for almost a year. It's rather short (8 exits), and it doesn't contain many fancy custom GFX, let alone custom music, but there's one thing that makes it special: Every level has a unique gimmick programmed with ASM. Kind of like "Brutal Mario", just not as advanced. For example, there will be the feature to play as Yoshi, doors that teleport you by scrolling the screen, and many more.
Really cool hack! I'm just leaving a comment to say there's a glitch in the final screen where if you're big mario, you get softlocked in that screen forever, so if you play this try that doesn't happen to you