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