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