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