When you hover over another player, their name will appear in red, white, purple or several gradients of blue, depending on their alignment. An individual's alignment can range from -1000 to 1000.
The bottom of your minimap will tell you precise alignment related information relative to your location.
New players will have an alignment value of 200. You can find your own alignment by looking at the bottom bar in your status window.
Any player that has a positive alignment can go rogue "grey" if they attack another player that has a positive alignment.
Characters who are in positive alignment are considered "blue", and players who are in negative alignment are considered "red". Only blue players are allowed to be in starter zones and racial capitals. Guard towers will attack any red or grey players as soon as they near these cities. These towers are very dangerous and will most likely kill anyone in a matter of seconds. Even with these towers, keep in mind that no place in the world of Agon is 100% safe!