Here is the full list of all 12 Who Wants To Be A Millionaire: Special Editions achievements.
Choose to Walk away between 32,000 and 250,000 (single player game)
Choose to Walk away with 500,000 (single player game)
Fail to answer the Million – dropping to 32,000 (single player game)
Walk away with nothing (single player game)
Use a lifeline (single player game)
Win 1,000,000 with all three lifelines remaining (single player game)
Win 1,000,000 (single player game)
Get to the Million Question -Tier 15 (single player game)
Reach 1,000 (single player game)
Answer the first question correctly (single player game)
Win "Fastest Finger First" Round in under 4 seconds (single player game)
Get the first question wrong (single player game)