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