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