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.
Review Paula's project plan.
Finish all of the Side Stories.
Love, Monika
Spend 20 minutes listening to music on the desktop.
Delete Monika twice while getting deleted zero times.
Find Dan's special note.
Ruin the game.
Listen to a lot of what Monika has to say.
Write a perfect poem for Monika.
Start a New Game.
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.
Write a poem in 20 seconds or less.
Write a perfect poem for Sayori.
Write a perfect poem for Yuri.
Write a perfect poem for Natsuki.
Spend enough time during the poem minigame for the music to loop.