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