it's the 8th in the series and it's darn hard!
walkthrough here for those who need it.
1: Right in the middle of the the floor, visible
2: Between window & flower container, on the floor
3: In 4th flower (from the left)
4: Between "L" and "C" on "WELCOME" sign
5: Behind "key box" (white box which shows amount of keys - below right corner)
6: From house to bottom, count 3 wooden floorboards (the 1st after the flower container). Drag it to the left until you see the key
7: On the right side of the last key, you can drag down 2 "fakes" wooden floorboards, side by side. The left gives you a key and a "useless" button.
8: The right "fake" wooden floorboard that you dragged down gives you another key and a button (We will use it later)
9: Note the "Welcome sign" and see that the last "E" has some missing parts (compare it with the 1st "E"). That's because there's a yellow panel there. Click and drag the wall to find the key
10: Drag a 2nd panel to find key.
11: When the pool is full with water, there's another key floating in the left/upper corner
12: The front of the pool is also a panel. Drag it to the left to find key.
13: Drag the pool panel to the right and find a note. If you read and do the math, you'll find out that you have to push ONLY the 5th button (from left to right). If you press any other you lost all keys. When you press it, the wall will show you a poster. There's a key above the "N".
14: Also, there's a new key in the top right corner of the game screen.
15: The floorboard that you first dragged to left (item 6), now drag it to right. You'll see a white paper. Open it and drag the title "The Blah" unti you see a red button. Click it and close the paper. Now, remove to left the front of the flower container. Drag left the yellow button and see that a panel is moving on the poster. Click it and a new key will appear right side of the flower container thing, below the poster.
16: Drag the wooden floorboard again to left and click the right button (the one I told you about in item 8). The poster will change into a Batman poster, with a key in the end off his right wing.
17: Click on the bottom left corner of this poster to see a button and click the button. Now you are able to drag the panel up on the left wall (below the white box with key counter) and get another key.
If you read the paper on the floor and note the detached text, you'll note a hint. So, now, it's time to refresh. Press F5 (in Internet Explorer) and wait until game loads again. When you enter it again, you'll notice that the pool is now empty (just like said in the paper).
18: Now the flower are a little different... And the last flower has a new key.
19: Click the top right corner of the key counter box to find a button. Click the button and now you can drag left the drag yellow panel inside the pool and find another key.
20: The last key is in front of the Sun, hard to see but easy to take.
Now, you've finished!