Here is the full list of all 40 Lara Croft and the Temple of Osiris achievements worth 1,000 gamerscore.
Complete the Tomb of the Silversmith
Complete a Challenge Tomb
Get the most gems in a tomb in a local or online multiplayer game
Get the most kills in a tomb in a local or online multiplayer game
Complete the Tomb of the Timekeeper
Revive another player in a local or online multiplayer game
Unlock a treasure chest
Collect enough canopic jars to unlock an onyx weapon
Complete any red skull challenge
Finish any tomb in online multiplayer
Escape the Pyramid of Osiris
Wear two rings and an amulet
Find your first weapon
Complete all Challenge Tombs
Complete all challenges
Complete all Pyramid of Osiris challenges
Complete all Timekeeper challenges
Complete all Silversmith challenges
Complete all Khepri 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
Complete any level time challenge
Complete any gold score challenge
Bomb a player in a Magic Shield 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
Have the most deaths in a tomb in a local or online multiplayer game
Defeat Khepri
Complete the Tomb of the Ferryman
Complete the Tomb of the Lamplighter
Defeat the Oracle of Osiris
Defeat Sobek
Complete the Tomb of the Architect
Defeat the Pharaoh
Complete the Tomb of the Torturer
Defeat Set