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