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