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