Here is the full list of all 50 Flood of Light achievements.
First time to replay the level
The first time you submerged in water
Activate the Sky Prop
Collect a letter marked 01
Complete levels without closing tips
Pass through a huge advertisement board on 7F
Check the telescope at Elevator
Extract the power from The Code of Light
Choose keyboard control on pause page
Activate the Land Prop
Activate the Marsh Prop
Activate the Fire Prop
Activate the Wind Prop
Activate the Thunder Prop
Activate the Water Prop
Activate the Mountain Prop
Extract the power from The Code of Sea
Extract the power from The Code of Spirit
Acquire all Wicks
Complete RainDay with the 'Sunshine' Ending
Complete RainDay with the 'Regression' Ending
Restart the game after completed the Ending
Back to the game again
Gain a S stage glory on 8F
Gain a S stage glory on 7F
Gain a S stage glory on 6F
Gain a S stage glory on 5F
Gain a S stage glory on 4F
Gain a S stage glory on 3F
Gain a S stage glory on 2F
Gain a S stage glory on 1F
Gain a S stage glory on Ground Floor
Fix the first Robot you met
Fix ALL Robot
Fix Robot Chef
NEW_ACHIEVEMENT_DESC_1_30
Collect all 17 letters
Take or move light over 300 times
Take or move light over 666 times
Take or move light over 1000 times
Fly and place 20 lanterns
Complete 50% game progress
Complete 100% game progress
First time to replay completed chapter
Take lights from two different lamp posts
Take lights from three different lamp posts
Take lights from four different lamp posts
Check out the producer list
Complete task on 6F level without replaying
Complete task on ground level and gain the S stage glory without replaying