It's not visible on the store page of main game, so tough to locate for those interested. Doesn't look like it has achievements in that DLC, so a pass for me .

It's not very helpful. Since I don't know where the missing ones are (or I wouldn't need pointers), I have to zoom out all the way. Meaning, the things are REALLY small. And they flash ONCE on click. I had to make it beep A LOT to find the last two. And I had to be lucky to look in the right direction at the right moment. Sure, I could have zoomed in, but then I'd have to make it beep a lot AND move the visible part of the drawing all the time....

Is the DLC required to get 100% completion?

No files to download https://i.imgur.com/iIDnB6F.png From what i remember it's some mistake on uploading game by publisher

I see some placeholders (1 per month) in the menu select page. Please, PLEASE place achievements in upcoming DLCs; it motivates players to BUY them instead of just playing the free (base) game then run away.