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