In OGAT, there are many ways to start a game. You can either join one of the dedicated servers, which offer a mostly stable connection and a lot of space. However, these servers aren't moderated, so if you can't take some insults, you should avoid playing there.

Another possibility to start a game is to join one of the player hosted servers. They always have an admin, who might moderate the server and accept requests to gamemode and map. However, some of the admins have a bad internet conenction, so you might face a lot of lag in these servers. If you want to know, how laggy you likely will be before joining a server, look at the serverlist itself: The higher up a server is, the closer the admin is to your current position and the more likely you will have a good connection to it.

Finally there is also the possibility to host a server yourself. This enables you to decide freely about gamemode and map, but it also brings a lot of responsibility: You will have to moderate the server and watch out to keep the teams balanced enough to enable a fun game experience. This usually requires at least some experience, so I advice you to rather join other servers first to learn about proper balance in teams, mode and map.

This part serves the purpose to give a short information about the most common gamemodes.

GAT: In this gamemode, the guards have to guard the objects from the thieves, who want to steal one of the objects. Kills dont matter in this mode, so focus on the objective instead of trying to get as many kills as possible.

TDM: In this gamemode, both sides have to get as many kills and as few deaths as possible. While the guards have an advantage in a fair fight, the thieves can see in the darkness and strike from the shadow. As a thief, never forget to use the darkness to your advantage, while a guard should always watch out for dark areas.

DE: In this gamemode, the guards have to defend two spots ("A" and "B") from the thieves, who want to plant a bomb at one of these spots. If the bomb is planted, the guards have a limited window (about 40 seconds) to defuse the bomb, before it explodes. Like in GAT mode, the total ammount of kills doesn't matter, so focus on the bomb rather then on kills.

IG: Same as TDM, but each player has a gun which kills with a single shoot. So better watch out!

CTF: Each side has to steal the opponents flag by moving through it and bringing it to a "capture point", in order to gain score.

The guards job is to guard the area and kill whatever thief they find. They are heavily armed and stronger than the thieves in a straight battle. However they have the big disadvantage to not be able to see in the dark. As a guard, you should always watch out for dark areas, because a thief might hide within. Use the light switches, to make room bright and use your flashlight to see in dark areas. You should try to stay with your team, except the situation requires your imidiate intervention. In bright areas, you should turn off the flashlight (right click) in order to not tell the thieves too early, where you are. But do not forget to turn it back on, when you move into the darkness!

The thieves job is depending on the chosen mode. Normally they have to try to sneak around the guards, to get to a specific position. Thieves are much weaker in combat then guards, so try to avoid a straight battle. Their huge advantage is the nightvision, which they can use to see in dark areas. Always try to avoid light whenever possible and use the light switches to turn the light in bright areas off. If you can't avoid a battle, try to hit the guards from behind or set an ambush in a dark area, where the guard can't notice you fast enough, so you will hit him several times, before he can start hitting you. Try to avoid rushing, because thieves can only take a few hits and deal few damage. It is not always smart to stay with your team as a thief, you can also try to get the enemy distracted, so a teammember can sneak throught the enemy lines. If you always stay patient and use the darkness, you will certainly like the thieves for the gameplay that requires a lot of tactics.

Note: Some of the pro players are actually skilled enough to use the thief classes as combat units. But only because they are skilled enough to rush on a guard and kill him, it doesn't mean you will be able to do it. Stay patient and concealed and your chances of victory will improve a lot. On the other hand you should avoid to just stay at one position all over the match. This isn't only boring but also not helpful for you or your team.

Grenades: Grenades are highly useful, but you shouldn't only rely on them, because they are slow and easy to dodge. Also they deal damage to your teammates, so watch out when using them! Same goes for stones, who might look funny but actually deal damage to your teammates when thrown at them. You don't want to accidentely kill a thief, who has almost escaped with the stolen object...

Vents: Although some of the pro players have learned a trick to sometimes shoot through some of the vents, a new player will usually not be able to do the same. So don't even try it, it's only a waste of ammo and time.

Names: You only see the names of your teammates floating over the char. So if you see someone with a name over his head, he is a friend - don't shoot him! The names change the colour, depending on how damaged a palyer is. This is helpful when using the medic class. Yellow means lightly wounded, while red means heavily wounded. If someone is green, he isn't wounded.

Medics: In order to heal someone, medics have to use their gun or syringe, to hit the player. This doesn't mean, that they attemp to teamkill you, they only want to heal you. So no reason to kill the doctor, only because the syringe hurts ;)

I hope this guide will help you discovering OGAT. I didn't mention all mechanics, nor all tricks ever invented, but don't be afraid to ask players you meet. Most of them are friendly and will try to help you, if you behave friendly too. It might also be a good idea to look for a clan. Only few of them take newer players, as far as I know the clans interesting for newer players are:

Free Gamers United (Ask Idulus, good behaviour required)
BTP (Ask Netto, french clan)
Klepto (Ask Flinn, a certain skilllevel required)

Don't give up, if you don't win every match or meet pro players, who will kill you with their high experience. Everyone once started as a newbie, even the best of the best. Always remember, that OGAT is only a game and that you will become better, if you play it for a while. Also don't feel sad, if you get kicked from some of the servers. Some admins don't want low level players on their servers, because they are too skilled, so newer players won't stand a chance against them. Some also need space for their friends, some think, that your ping was simply too high. However, most of them don't actually hate you or something. Just try to join another server.

I wish you a lot of fun with Of Guards and Thieves!