Cosmic Break never seems to have any trouble introducing new characters, unlike some games which always have to stretch the storyline a little bit. This is the case because the frame story is set up such that all robots are called into service from different planets, providing an easy way to add new content. New character? Discover another planet.
In an interesting tangent, I’ve noticed that the structure of most roleplays fail to include this sort of mechanism, which results in a great deal of stalling, either due to waiting on people who are on hiatus or trying to keep up with over-active posters. Typically, the DMs who run the roleplay lack the foresight to implement any sort of system beforehand and attempt to fix the stalling after it occurs with systems that just cause more stalling. Would it be so much of a stretch to say that every roleplay must include a mechanism of this nature? A little bit of foresight can save a lot of grief later on.