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