Pool Party

To clarify Richard's last spoiler (which is essentially the big spoiler of the game), and to include some terminology suggestion and explanation of what is happening, please read the following two spoilers (spread over two comments):

Spoiler: Terminology: "Run Around"

In Richard's initial hint, he pointed to Meko's Shortcuts level as an example of the technique that would have to be known in order to solve this level. I'll probably put some comment there to this effect as well.

What I'd like to propose is that we call Meko's discovery the "run around" trick. It is essentially yet another variant of an exploit of the path completion algorithm in the game. That is to say: that B will always do his best to get to the spot that you've tapped him to go to. In this case we need to exploit the fact that R can get in B's planned path and then B will have to find a way to run around R. Meko considered it as B taking a shortcut around R, and in a sense B is trying to compensate the fact that R has gotten in his way by taking the shortest route to the intended destination - and this includes overcoming single height obstacles, etc.

Since we already use the term "shortcut" in a level to imply finding a different (and often shorter) solution to a level from the one that the author intended, I think we should adopt a different term to describe the trick of forcing B to take an alternate route around R. Hence my suggestion of calling it the "run around" trick.

Part 2: what is going on here:

Spoiler: Exploit in the context of this level

So in Richard's last spoiler to TR O, he described what you would need to do to get B into the empty pool. The first step would be to get B over to the far side of the pool, i.e. along the edge of the game space near the corner of the house. This sets B up for a single path back to the other pool should you want to send him that way. More importantly, it means that if and when R would step to the opposite corner of this pool (and thus block off this one and only path for B), B would have to try to get around R with little option other than to consider the wedge block leading to the pool. It turns out that this wedge is acceptable enough for B to attempt in order to get around R. Stepping on to the wedge destabilizes B and he falls into the pool.

@meko We've found 3 other ways to complete it, so it's still possible.