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