Here is the full list of all 50 Silent Hill HD Collection achievements worth 1,000 gamerscore.
Acquire the Dog Key.
Acquire the Chainsaw.
Find at least 150 items + extra items in SH2.
Defeat Abstract Daddy.
Acquire the Silencer.
Acquire the Beam Saber.
Acquire the Gold and Silver pipes.
Defeat Missionary in under 2 minutes.
Defeat Memory of Alessa in under 3 minutes.
Defeat at least 75 enemies by shooting in SH3.
Unlock the "In Water" ending.
Unlock the "Maria" ending.
Defeat at least 75 enemies by shooting in SH2.
Unlock the "UFO" ending.
Receive less than 500 points of damage in one game, in SH2.
Acquire the Blue Gem.
Unlock the "Born from a Wish" ending.
Unlock the "Rebirth" ending.
Acquire the book of Crimson Ceremony.
Complete Boat Stage in less than 1 min 20 seconds.
Unlock all Achievements in SH3.
Receive less than 500 points of damage in one game, in SH3.
Complete SH3 in 3 hours or less.
Complete SH3 with 2 saves or less.
Unlock the Heather Beam.
Acquire the Obsidian Goblet.
Defeat at least 75 enemies by fighting in SH2.
Acquire the book of Lost Memories.
Acquire the White Chrism.
Acquire the Flamethrower.
Unlock the "Possesed" ending.
Defeat at least 75 enemies by fighting in SH3.
Acquire the Unlimited Submachine Gun.
Unlock the "Princess Heart" costume
Unlock the "Normal" ending.
Defeat God in under 8 minutes.
Defeat Leonard in under 3 minutes.
Pick up at least 100 items in SH3.
Defeat Split Worm in under 2 minutes.
Unlock the "Leave" ending.
Defeat Mary.
Defeat Pyramid Head.
Defeat Flesh Lips.
Unlock all Achievements in SH2.
Unlock the "Dog" ending.
Complete SH2 in 3 hours or less.
Acquire the Green Hyper Spray.
Complete SH2 with 2 saves or less.
Complete SH2 on Extra Riddle difficulty.