Here is the full list of all 49 Deus Ex: Human Revolution achievements. It takes around 40-50 hours to unlock all of the achievements on Windows.
You watched the entire credit list and saw the surprise at the end.
Complete Deus Ex: Human Revolution.
You defeated Zhao Yun Ru and by doing so, destroyed the Hyron Project.
You pointed out the flaws in his logic to millionaire Hugh Darrow.
Perform 50 takedowns within the same playthrough. (Civilians don't count.)
You defeated Jaron Namir, Leader of Belltower's Elite Special Operations Unit.
You convinced Mengyao to spill the beans on the mysterious Hyron Project.
Protect a client's interests by performing a less-than-hostile takeover.
Against all odds, you saved Faridah Malik's life.
You talked Doctor Isaias Sandoval out of suicide.
Help Officer Nicholas take out the trash.
You defeated Yelena Federova, elite member of a secret mercenary hit squad.
Successfully hack at least 50 devices within the same playthrough.
Fully upgrade your first augmentation of choice.
Help a lady in the oldest of professions clean house.
You sent Diamond Chan on the trip of a lifetime.
It may take some sleuthing, but justice must be served.
You really nailed your case against Lee Hong.
Help the Hive Bartender settle a tab.
You paid poor Jaya's debt in full. How very... humane... of you.
You convinced a fast-talking bartender to let you see Tong Si Hung.
You defeated Lawrence Barrett, elite member of a secret mercenary hit squad.
Deal with the man in the shadows.
Put a grieving mother's doubts to rest.
You convinced Wayne Haas to let you into the morgue.
Upgrade your first weapon of choice.
Deal with Mr. Carella's indiscretion.
You convinced Zeke Sanders to let his hostage go.
Perform your first Hack successfully.
You made it through an entire hostile area without making so much as a squeak.
Perform your first Takedown. Civilians don't count, so be nice.
Knock out at least 100 enemies in a single playthrough.
Complete Deus Ex: Human Revolution at its hardest setting.
Experience all the different endings that Deus Ex: Human Revolution has to offer.
Complete Deus Ex: Human Revolution without anyone dying by your hand. (Boss fights do not count.)
Complete Deus Ex: Human Revolution without setting off any alarms.
Read all 29 unique XP books within a single playthrough.
Follow Pritchard's lead to uncover the truth.
Descend into the bowels of an urban jungle and confront a warrior-priest.
Fully upgrade one of your weapons.
You found all the hidden story items in Megan's Office. Point-and-Click much?
You had an argument with your boss, David Sarif, and won.
You convinced the smooth-talking politician Bill Taggart to tell the truth in public.
You found and read the secret message. Now you know too much...
You kept Megan's bracelet for yourself. Apparently, letting go really is the hardest part.
Greedy bastard. You accepted O'Malley's blood money and let him go.
Maybe next time, Jacob will use a more complex code when arming a bomb.
You granted a dying man his final request.
Seems you like playing with balls, eh?