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