Here is the full list of all 19 Doki Doki Literature Club Plus! achievements. It takes around 6-8 hours to unlock all of the achievements on Windows.
Achieve 100% data collection.
Finish all of the Side Stories.
Spend 20 minutes listening to music on the desktop.
Find Dan's special note.
Review Paula's project plan.
Write a perfect poem for Yuri.
Delete Monika twice while getting deleted zero times.
Love, Monika
Ruin the game.
Listen to a lot of what Monika has to say.
Write a perfect poem for Monika.
Write a perfect poem for Natsuki.
Write a poem in 20 seconds or less.
Draw boxes on the desktop.
Choose not to quit DDLC.
Your desktop wallpaper could not be changed due to an administrative policy restriction on this computer. For more information, contact your system administrator.
Start a New Game.
Write a perfect poem for Sayori.
Spend enough time during the poem minigame for the music to loop.