Well, i created shifting, emulating and unstable mass at the same time as some kind of "cycle" which rewards carefully management of your hand, although i forgot to add a bricks-only one.
Shifting mass has got the most attention of them (because its the best useable and most impactfull one, you almost always clone the card with the most impact in both players hands) and in the end got added to the game.
Sometimes, i polish the texts of my old concepts to make the cards more clearly