Here is the full list of all 40 Lara Croft and the Temple of Osiris achievements worth 1,000 gamerscore.
Defeat Set
Complete the Tomb of the Architect
Complete all Challenge Tombs
Defeat the Pharaoh
Have the most deaths in a tomb in a local or online multiplayer game
Complete the Tomb of the Torturer
Defeat Sobek
Defeat the Oracle of Osiris
Complete the Tomb of the Lamplighter
Complete the Tomb of the Ferryman
Get the most gems in a tomb in a local or online multiplayer game
Finish any tomb in online multiplayer
Complete all Khepri challenges
Complete any level time challenge
Defeat Khepri
Complete any gold score challenge
Complete the Tomb of the Silversmith
Complete a Challenge Tomb
Complete any red skull challenge
Complete the Tomb of the Timekeeper
Wear two rings and an amulet
Unlock a treasure chest
Escape the Pyramid of Osiris
Find your first weapon
Collect enough canopic jars to unlock an onyx weapon
Complete all challenges
Complete all Pyramid of Osiris challenges
Complete all Timekeeper challenges
Complete all Silversmith challenges
Complete all Ferryman challenges
Complete all Lamplighter challenges
Complete all Sobek challenges
Complete all Architect challenges
Complete all Torturer challenges
Complete all Set challenges
Bomb a player in a Magic Shield in a local or online multiplayer game
Revive another player in a local or online multiplayer game
Finish a tomb in a 4-player local multiplayer game
In a 4-player local or online multiplayer game, be the only player to not die in a tomb
Get the most kills in a tomb in a local or online multiplayer game