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