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