[swfn]

That sounds very interesting, many thanks for all the explanation. Precisely I was watching a couple of days ago a tutorial and indeed does not seem that difficult once you are used to all the features. There are already sets of movements available (mainly to make the characters dance), which makes things easier.

I have also seen that you can even change at will the facial expressions of the characters at any point, which answers the question of Raso719 and OhZone: yes, it is possible to make them look scared or shocked, touching themselves, etc. while they are shrinking, but this seems to require quite extra work.