The Go-Go Bar gives you the chance to test your base defenses in simulated combat. Because you can run as many of these simulations as you like without doing any actual damage to your base (there are no repair costs), this is one of your best tools for figuring out how various defenses interact with different types of attacker.

To use the Go-Go Bar, click on it and look for the Open button.

A window will appear that gives you all the options for testing your defenses.

What you are doing in this window is building a platoon that will attack your base from a specific direction. You can either click on the individual unit types to add them to the attacking platoon (you can change the quantity of each unit as well), or you can use the Randomize button indicated by arrow A. Then, click on the direction you want the attackers to come from when they hit your base (arrow B); this can also be randomized. Finally, when you're ready to run your simulation, hit the Test Defenses button (C).

You'll then see a brief countdown, and the simulated battle will begin! You can control your Base Defenders manually, or you can use the game's AI RUBI to set their defensive or offensive posture and watch them just do their thing. The battle will run until the attackers have destroyed your base or have been destroyed themselves; you can also stop the simulation at any time by using the Stop feature (see arrow B below).

When your Go-Go Bar reaches level 21, you will be able to use that Swap arrow (A) to toggle control between your Base Defenders and the attacker; this makes it even easier to test specific strategies and attack vectors.

The Go-Go Bar also provides a couple buffs for your Base Defenders platoon. Depending on its level, the Go-Go Bar increases the amount of damage done to attackers by your Base Defenders, and reduces the amount of time it takes to repair them. As above, these bonuses are not cumulative; the number shown here is the total bonus at the indicated level.