Here is the full list of all 35 Disc Room achievements.
SURVIVE 20 SECONDS IN EVERY ROOM
EXPLORE ALL ???? ROOMS
EXPLORE ALL HARD ROOMS
SURVIVE 20 SECONDS IN ANY HARD ROOM
COMPLETE HARD MODE
SURVIVE 10 SECONDS IN EVERY HARD ROOM
SURVIVE 20 SECONDS IN EVERY ROOM IN ONE ZONE
DEFEAT THE ULTIMATE GATEKEEPER USING EVERY ABILITY
UNCOVER THE GOLDEN MYSTERY
DIE FROM 4 DIFFERENT DISCS IN ONE LIFE
EXPLORE ALL ROOMS
DIE FROM ALL DISCS
DISCOVER THE FOURTH GOLDEN ROOM
FACE THE GOLDEN CARCASS
FOLLOW THE PATH
START HARD MODE
DEFEAT THE ULTIMATE GATEKEEPER
???? THE ????
DEFEAT AND REVIVE AN ANTIBODY
WALK 10K STEPS
UNLOCK ALL 6 ABILITIES
DISCOVER THE THIRD GOLDEN ROOM
DEFEAT THE PHANTOM GATEKEEPER
DEFEAT THE CARNIVOROUS GATEKEEPER
DISCOVER THE SECOND GOLDEN ROOM
HOLD DOWN FFW FOR 10 SECONDS STRAIGHT
SURVIVE 60 SECONDS IN ANY ROOM
QUIT TO MAIN MENU WITHIN 2 SECONDS AFTER DYING
FEED ???? 4 ????
DIE FROM ALL DISCS IN ONE ZONE
DISCOVER THE FIRST GOLDEN ROOM
DEFEAT THE OVERGROWN GATEKEEPER
END A RUN FROM THE MAP
SURVIVE 0 SECONDS OR LESS
DEFEAT THE ARMORED GATEKEEPER