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 the hard way.
Rescue 10 or more damsels in one game.
Reach the Jungle.
Reach the Ice Caves.
Reach the Temple.
Complete the game.
Obtain 500,000 gold.
Reach the City of Gold.
Obtain the Ankh.
Complete the game without using shortcuts.
Complete the game in under 8 minutes. No shortcuts.
Play Adventure Mode 1000 times.
Complete 50% of the journal.
Complete 100% of the journal.
Kill 12 or more shopkeepers in one game.
Complete the game without collecting any treasure. No shortcuts.
Complete the game with at least two players alive. No shortcuts.
Win the kapala from Kali.
Rescue all 16 hidden characters.
Beat the Tutorial.