Here is the full list of all 35 Drilly Willis achievements.
DEFEAT 50 ENEMIES WITH YOUR DRILLHEAD
DEFEAT 150 ENEMIES WITH YOUR DRILLHEAD
DEFEAT 300 ENEMIES WITH YOUR DRILLHEAD
DEFEAT 50 ENEMIES WITH YOUR SCREW SHOOTER
DEFEAT 150 ENEMIES WITH YOUR SCREW SHOOTER
DEFEAT 300 ENEMIES WITH YOUR SCREW SHOOTER
JAM 50 SONGS ON YOUR GUITAR
JAM 200 SONGS ON YOUR GUITAR
JAM 400 SONGS ON YOUR GUITAR
DIE 50 TIMES
DIE 150 TIMES
DIE 300 TIMES
DISCOVER 30% OF ALL ROOMS
DISCOVER 60% OF ALL ROOMS
DISCOVER 100% OF ALL ROOMS
FIND 30% OF ALL ITEMS
FIND 60% OF ALL ITEMS
FIND 100% OF ALL ITEMS
GRAB YOUR GUITAR
ROCK 50 ENEMIES
ROCK 150 ENEMIES
ROCK 300 ENEMIES
BUILD YOUR FIRST UPGRADE
FULLY UPRADE DRILL POWER
FULLY UPGRADE DRILL SPEED
FULLY UPGRADE SCREW SHOOTER POWER
FULLY UPGRADE SCREW SHOOTER SPEED
FULLY UPGRADE GUITAR CHOPS
BUILD ALL UPGRADES
EARN ALL ACHIEVEMENTS