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