The Great Steam Treasure Hunt was an event on Steam that started on the 6th December 2010 and ended on the 20th December 2010.
A total of 28 objectives were included in the event. 10 entries plus logging in on the 20th entered you into a draw to win 100 games, which 3 people won.
A daily drawing was also held, where 20 winners won the top 5 games in their wishlist every 2 days, to qualify you had to have at least one of the current objectives, and at least 10 games on your wishlist.
Also, 3 Team Fortress 2 hats were given to people that got a certain number of objectives.
Set up an avatar.
Become a Desert Fox in R.U.S.E.
Up the Ante
Unlock The Iron Curtain in Poker Night at the Inventory.
Set a leaderboard score of at least 1,124,400 in easy mode for the 'Paul Hartnoll' level in Chime.
Friends with Benefits
Have 10 friends on your friends list.
What Happens in Vegas
Complete Ol' Buddy Ol' Pal achievement in Fallout: New Vegas.
Set a leaderboard score of at least 22,600 on the level 'Mash Face Against Mountain' in AaAaAA!!!.
Go To Your Happy Place
Play the demo or game The UnderGarden.
Join the Club
Join an official group.
Get Back in Business in Mafia II.
Stack the Deck
Be a Devastator in Magic: The Gathering.
Just Drop It
Set a leaderboard score of at least 85,370 for 'Classic - Small Wonder' in Droplitz.
It's Better to Give
Send a gift to a friend.
Take One for the Team
Make a Sacrifice in Call of Duty: Black Ops.
Set a leaderboard score of at least 11,200,000 for 'Bonus Mode' in Shatter.
Create a Crass Menagerie in Left 4 Dead 2.
Watch the trailers for Deus Ex: Human Revolution, Homefront, BRINK, Red Faction: Armageddon, Warhammer 40,000: Space Marine and Portal 2.
Become a Nosalis Hunter in Metro 2033.
Cause and Effect
Create a Destruction Frenzy in Just Cause 2.
Set a leaderboard score of at least 3,770,488 for 'Survival Best Score' in Beat Hazard.
Post a comment on a friend's Steam Community profile page.
One Hit Wonder
Build a Wonder in Civilization V.
Set a leaderboard score of at least 10,515 for 'Slaughter, City Center' in Zombie Driver.
Butter Me Up
Build Me Up Buttercup in Bob Came in Pieces.
Write a recommendation.
Made in the USA
Become a Founding Father in Empire: Total War.
Buzz the Tower
Set a leaderboard score of at least 37 for 'Beach' in Flight Control HD.
Played at least 15 games or demos since March 2009 (When Steam began recording playtime).