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