No, this week's title has nothing to do with Wookiees or Ewoks, unless you want it to. It ties to something Clone Wars Supervising Director Dave Filoni said in the commentary of the Clone Wars episode, Altar of Mortis. For those who haven't seen it, and no spoilers here, the Mortis trilogy delves in to the supernatural side of the Force way more than usual. It's something we've really only seen in the extended universe, and reminds me more of the Knights of the Old Republic era or some of the scenes in the more recent Fate of the Jedi novel series. Anyway, Filoni said to his writer to treat the episodes like they are all within the tree* from Empire Strikes Back, and that they're full of metaphor and, I presume, illusion.
Heavy metaphor and the supernatural are not something the Star Wars Roleplaying Games typically focused on. There are discussions of it, enough so that GMs can build their own adventures around aspects of it. The early WEG adventure Domain of Evil** dealt with these themes (sorry, can't get into details - I don't have a copy). Most examples in the game are of single scenes like the tree in Empire, but with the Mortis trilogy, it opens up the scope and scale of such adventures.
So, how do you, as gamemaster, introduce supernatural aspects into your game, and go adventuring in the tree?
First, you need a location with a strong dark side connection. It's not necessary that the players understand what that connection is, though you can build that into the story if you like. In Saga Edition, you can get some advice on dark side sites from the Jedi Academy Training Manual, page 156. Suffice to say that something tainted the area with the power of the dark side, usually something extraordinarily bad.
Next, you need some Force sensitive player characters. It's not definitively shown these affect only Force users, but we haven't seen it on screen. Therefore, it's up to the GM as to whether they want to include non Force users in any visions, illusions or similar scenes.
Now for the hard part. You need a metaphor. This kind of scene typically shows a possible future - a bad future - for the player involved. You need to have some idea what the character is afraid of, and use that against them. In the tree, Luke probably never considered that he could supplant and virtually become Vader, until it was revealed to him. So, if you can not only show the character the results of their greatest fear, but results they had not considered, it will be more powerful. Showing them becoming the face of evil should be more dramatic than it will be (they've seen Empire, after all), but showing them becoming evil and corrupting a friend or loved one in the process might have a bigger impact. Infighting between friends, allies or groups is another possibility.
Last, you need to decide how long the characters are in the tree. A single scene? An entire adventure? Also, how much is real and how much is illusion or vision? What happens afterwards?
The easiest example for this kind of game play is Luke's encounter in the Empire Strikes Back. It's highly limited in time (just a few minutes, or a single scene) and scope (it includes only one "player" character). This kind of scene is fairly easy to drop into a game for a single Force user with minimal disruptions in time and story.
A similar example is the dream/vision, with the added benefit that the story and events can get really weird and then written off as dream later on. This works best with a single character, though the shared dream experience is always good to creep characters out.
Finally, there is the Mortis example. Here, it includes several Force using "player" characters, obviously interacting with both the environment and each other. It has a confusing arrival sequence. It has embedded dream and vision sequences. It's long term with a lot of unusual effects going on. While treating Vader as non-speaking illusion in the tree is one thing, meeting and interacting with brand new characters is something else entirely. Also note, as of this writing, the last episode isn't out yet, so the ending is unknown (probably should have waited until next week...oh well. I'll update it somehow). It's the kind of environment a GM could do virtually anything with, in the short term.
One other thing...before embarking on this kind of adventure, the GM should know if his or her gaming group will like it. Some players - often those who don't play Jedi - really don't care for the mystical side of the Force, and may be put off by the change in tone and subject matter. If you have such a group, go for the limited sequences like the tree. Also, keep in mind what era you're playing in. In my mind, this works best in the KotoR, Legacy or NJO eras, ok in the Clone Wars era, and not as well in the classic era. Your mileage may vary.
* Yes, technically a cave under the tree, but just roll with it.
** Sometimes I run across really useful sites and forget to mention them. This week I was trying to remember the name of Domain of Evil and ended up at the racorpit, a d6 site I haven't visited in awhile. Anyway, among their many items, they have the covers of all the d6 Star Wars books, very easy to find that pesky cover you remember, but mixed up the the name with another product...
FYI, starwars.com just posted a piece summaraizing some of George Lucas' comments on the Force over the years. GMs (and others) may find it useful.
With the conclusion of the Mortis trilogy, I don't see anything to change my comments above. It just reinforces the fact that you could have an entire adventure within the tree, and have it take as long or as little time as you want in the "real world."