Knuckle Cracker

Now that that's over with, let the exposition begin. If you wish simply to know the solution, I will tell you. Click an orange button in the top right corner of the menu screen before playing. Why this works, and how, are very important points to make. Double Down, as it is called, can be unlocked by finishing the last 2 Special OPs missions, although in order to do so, you must finish every conquest map. The question then becomes one of what it does, and how you can use it to your advantage. Some testing in the included maps reveal that it seems to make the creeper stronger, and so many people only turn it on when they want an extra challenge.

While that may seem to be all, if it were, you would not only lose, but lose faster. Clearly there is more to it. Using the marvelous power of the custom map editor, one can perform more precise tests. Upon doing so, one sees the effects more directly. As it happens, Double Down decreases the amount of time between emitter firings by 50%. Since emitters produce creeper, this works against you. There is still no obvious reason for this to save you. However, careful examination of the emitter firing procedure allows you to see what is really going on here. When an emitter fires, rather than adding its intensity to the creeper levels above it, it replaces the creeper level above it by its intensity. This means that a 0-intensity emitter removes all of the creeper above it when it fires. Since they fire twice as often, less creeper can get in, even though there is more on the outside.

The final piece of the puzzle comes with the knowledge that the creeper only updates its flow every 7 frames, or about 1/5 of a second. This is the reason 0.1 interval emitters seem to not be much stronger than 0.2 interval emitters until you attempt to cap them. Since these emitters fire roughly every 2/5 of a second, setting them on double speed means they delete creeper before it can spread to the other side.

The only question that remains is as to whether or not it is worth using on any given map. There are not very many that you benefit in this way from, but they do exist.