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