(Causatio boom boom)
As you can easily imagine, when an Ingredient marble is removed from the slide during a regular pick, all the marbles above it with roll down to fill the gap. This is when an Explosion can occur!
1. The red marble is taken and starts a chain reaction.
If two Ingredient marbles of the same color collide, they explode. When two Ingredients explode, all of the Ingredients of that color connected to them also explode. You take all of the exploding Ingredients, just like the one you directly picked from the Dispenser.
Don't forget that Explosions only trigger if the ingredient was picked as the regular pick of the turn.
2. The three yellow marbles collide (and explode). They are all taken.
If, after removing all of the exploding Ingredients, there is another collision between marbles of the same color, this new collision will trigger another Explosion, and you also take all of those exploding Ingredients. If, after that, another collision between marbles of the same color occurs, a third Explosion will happen, etc.
3. Next, the two black 3 marbles collide and explode. They are also taken.
Not all students notice this at once: when there are three or more connected marbles of the same color, if you pick one of those from the middle, you still trigger an Explosion by making the others collide! That’s a pretty neat move, don’t you think?
4. No more marbles of the same colour collide. The chain reaction stops.
Note that those two blue Ingredient marbles in the last step of the example - even though involved in a collision—do not explode. An Explosion occurs only when two or more marbles of the same color collide with each other. Moreover, if you trigger a particularly big chain of Explosions, one or more slide tracks can end up being partially empty. This is not a problem.