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