Professor Layton, you cheat!

Sorry I haven't been around much, this is my error in judgement.  Having gotten into Livestreaming my gaming sessions, I'm without any spare time!  I work all day, eat, then stream.  My weekends go towards grocery shopping, cleaning the house, spending time with family/friends/relationship/etc... I don't get a chance to just sit down and type, really.

It's a genuinely poor excuse, I know, because what I'm about to type just screams "You do so have spare time!" Hahaha.

So, while at work doing nothing, I've been playing some ROM's of Nintendo DS games.  Mostly because, I've heard a lot of chatter about these games, and I do not own a DS (Oops).  I've been playing Phoenix Wright - Ace Attourney on my OUYA and it's great fun, I can't wait to get into the other games.  But Professor Layton I've been playing at work since you need to use a stylus (So I use a mouse, of course).

I've come across a puzzle that just pisses me off.  Puzzle 076 "A Tile Square"

Here's the problem:

So the problem here is to *make a square.* Before you see the solution, note that the solution the game provides you is, in fact, a square (and not a cube).  The second hint tells you that "the puzzle also shows you the thickness."  Kind of a leading hint to use the thinkness, no?

Well, here's the problem.  I have three solutions to this puzzle, and the one the game wants is not the right answer.

The first answer I came up with, was 18 tiles.  Make a hollow square with 6 tiles on the left and right, and 5 tiles across the top and bottom (Don't count the corners twice!).  This is 18 tiles of 60x60 inches.


But, not the solution.

So the second hint refers to the thickness?  Okay then, got it!  Put the tiles vertically up, and make a square.  Like this:



Doesn't matter the side length, be it 10 or 12 inches.  But now it's a square 10.5 (or 12.5) every side.  Brilliant, right?  4 is the answer!  ...NOPE!

The answer is 20!  What?!

Uh what?  It's not even a cube, it's still a square... 10x10 inches.  Really developers?  Twenty tiles?  Terrible question!!