Super Meat Boy has just been updated with new achievements, and though they are listed on the steam achievements page, they have no accompanying text on how to unlock them. The original secret achievements, the so-called cryptic, glitched achievements have already been identified elsewhere on. NiceStickman Super Meat Boy 48 achievements 79.16% done 11h 12m played.
Salt Boy – Complete the Salt Factory without dying.
Brimstone Boy – Complete Hell without dying.
Maggot Boy – Complete the Rapture without dying.
Dead Boy – Complete The End without dying.
Nostalgia – Unlock a single retro warp zone.
Living In the Past – Complete 5 retro warp zones.
Old School – Complete 10 retro warp zones.
Retro Rampage – Complete all retro warp zones.
The End – Beat the light world.
The Real End – Beat the dark world.
Golden God – 100% the game.
I Have Crabs! – Unlock the Head Crab (10 bandages).
Metal Head – Unlock the Machinarium Robot (30 bandages).
I Smell something Fishy… – Unlock Naija (50 bandages).
MS PAINT RULZ! – Unlock RunMan (70 bandages).
Vx6 – Unlock Captain Viridian (90 bandages).
Accidental Arsonist – Unlock Mr. Minecraft (100 bandages).
The Commander – Unlock Commander Video.
The Bootlicker – Unlock Jill.
The Jump Man – Unlock Ogmo.
The Fly Guy – Unlock Flywrench.
Super Meat Boy Achievements Steam Cleaner
The Kid – Unlock the Kid.
There's also one achievement apiece for beating the secret levels, -1 through -6.