Here is the full list of all 20 Spelunky achievements. It takes around 100-120 hours to unlock all of the achievements on Windows.
Complete the game with at least two players alive. No shortcuts.
Rescue all 16 hidden characters.
Complete 100% of the journal.
Complete the game without collecting any treasure. No shortcuts.
Obtain 500,000 gold.
Complete the game the hard way.
Play Adventure Mode 1000 times.
Kill 12 or more shopkeepers in one game.
Rescue 10 or more damsels in one game.
Complete the game.
Complete the game without using shortcuts.
Complete the game in under 8 minutes. No shortcuts.
Reach the City of Gold.
Reach the Temple.
Reach the Ice Caves.
Obtain the Ankh.
Complete 50% of the journal.
Win the kapala from Kali.
Reach the Jungle.
Beat the Tutorial.