Be warned, that set of tests will be launched against you before final decision is made, and wannabe-GM is never informed about results. Some of them are created by devs, some by already appointed GMs, some are easy to spot, some are harder, all of them have one thing in common - they always happen in same location, and check how you react - do you move or not. Usually these invented by current GMs are hardest. Anyway, if you move, you fail the test and next one will be launched after undefined amount of time. Look at Shady Sands. Now look at Hub. Now back to Shady Sands. See all these idlers, which never visit Hub, but always stick to Shady Sands? Remember how many weird things happens in there? Coincidence? I don't think so. You may not belive, i understand that. Ask people which was playing back in 2009 how i became GM, but i assure you that you will hear "she just stand at one spot in Shady Sands, all days long".
Once you complete basic tests, you will be removed from Shady Sands and put in very specific map for final test. Being separated from hex you choose is harshest thing in wasteland, nothing you experienced as a player can be compared to that. Many, many people resigned at that stage, and did whatever it takes to get back to the hex. Even after more than 2 years, it's hard for me to write about that time, let's focus on map. Once you are teleported to HELL (that's how map was named by first GMs), you will be asked if you want to be Game Master. In theory you have unlimited time to answer, but keep in mind that person which summoned you wants to go back to own spot. Don't be evil yet. There will be time for that.
Take a look at how map looks like (http://fonline2238.net/~wipe/slave.png). As you can see there is few NPCs and container. NPCs role is to simulate what will await you as a GM. NPCs will ask for skins, free items, blame you for disconnects, demand refunds, flame about events and so on. Since we integrated the map with forum, it's possible to redirect posts content, or whole threads to NPC. Attached script will extract most interesting parts basing on set of keywords and filters (it's probably going to be changed, GM candidates always fail since it was implemented). Stay strong, don't leave the hex on which you has been put, or you loose your chance. (Sidenote - from time to time GM/dev will drop in to say hello and/or drop items stolen from bases/tents into container. If you are a person with good manners, you'll welcome him/her with Game Master Creed (see below); it's not required, just a part of tradition) Other things will happen on map, but - sorry - can't post them here; it would give people chance to prepare for them and as i mentioned earlier, i want to forget again about time when i was so far from my lovely spot.
Game Master Creed
This is my hex. There are many like it, but this one is mine.
My hex is my best friend. It is my life. I must protect it as I protect my life.
My hex, without me, is useless. Without my hex, I am useless. I must always stand on my hex. I must shoot straighter than my enemy who is trying to replace me. I must shoot him before he push my character. I will...
My hex and myself know that what counts in this game is not daily solving others problems, the noise of our airstrikes, or infinite tests we perform. We know that it is idling what counts. We will idle...
My hex is human, even as I, because it is my life. Thus, I will learn it as a brother. I will learn its weaknesses, its strength, its pixels number, its graphic format, its xy position and sceneries placed on it. I will keep my hex clean and ready, as I am clean and ready. We will become part of each other. We will...
Before AHS-9, I swear this creed.
My hex and myself are the defenders of Shady Sands.
We are enemies of activity. We are the saviors of online players number.
We are Game Masters.
Once you complete the trial, you can take items put into container if you wish. You also get Server Crash Switch - name speak for itself, no need to explain what it does - and list of commands which are designed just to make players life harsher. They're kept for historic reason, since some time we use Abuse Menu for that.
The secret revealed. (http://i45.tinypic.com/ekf1cm.jpg)
I hope this short post answers your question and will help others looking for way into GM team. No additional info will be added - if you still don't know what to do, you are not ready yet. If you are, we will welcome you with open arms.
This is my story, this is a story of all GMs. Another secret revealed.