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