In contrary to the potential expectations considering the name,does not have very much in common with soccer or football (or even sports). Some elements have been adopted, though. Two teams try to put a ball into the enemy's goal while guarding their own.
The specific "rules" are completely different. That means almost everything is allowed. You can run as far as you want and get with the ball in your hands. The enemy tries to stop you by hitting, kicking, using swords or even flame and bomb throwing at you. This violence can also be used as a reason for itself: Instead of scoring more goals than the other team, you can kill all enemy players in the preset time. That is done by reducing their energy to almost nothing and then beheading them bloodily.
There are different kinds of teams and you should change your strategy according to them. If the enemy has very fast, but weak players that score all the time, you should rather kill them all. If you play a team of musculous dragons instead, you should avoid direct contact as far as possible.
In the match different power-ups appear from time to time. These can be collected and then be activated when needed. For example you can freeze all enemy players for a few seconds or strike them down with lightnings. If you are not careful though, you sometimes get disadvantages like temporary slowness.
According the game's result you are paid some money afterwards that is used to heal/resurrect your hurt players. That works quite simple because they are supposed to be androids. If you lack the money to heal them all completely, you can as likely give up. So this option seems to be more than it really is. You have to restore your whole team completely in any case.
The common game modes exist: League, Knockout and single game ("Unfriendly"). There are no differences in the game itself.
It is almost impossible to describe whyis good. It is just fun! The simple concept is very approachable, but it is demanding later. You cannot play it for month, of course, but it motivates you for some weeks. And which new game can claim that?