Is EVE Online turn-based behind the scenes?

This came up as an argument. As far as I know most MMOs employ a soft "turn-based" mechanism to compensate for lag, and allow complicated actions to be performed ("cooldown" etc). They are sometimes called "tick based" systems as well.

Obviously EVE Online doesn't have a turn-based gameplay but does it employ turn-based game mechanics?

Otherise it means that faster internet connection or living in Iceland could be an advantage in combat.

Everything in EVE is based on a tick based mechanic. The implementation is very transparent unlike in some other massively multiplayer games but it is evident in many of the actions available in game. At the time of writing the tick speed is 1Hz. Most actions in EVE require a certain number of ticks to complete (collectively called cycles), the number of which are then modified by skills and items.

This is visible in every action - every time you target somebody, activate a module, etc - even changing direction in flight in that if you try to send too many movement based commands in quick succession they will begin to queue up (the queue is very short, so too many commands or overriding commands will result in actions being dropped from the queue) before being executed in the next tick.

For example; firing your weapons will activate a cycle. This cycle cannot be "cancelled" as cancelling it will still require the cycle to complete before you can start another. If the cycle completes in the middle of a tick, you will have to wait until the next tick before reactivating it and starting another cycle.

Additionally, the game employs a "time dilation" system in highly populated/active systems which applies a modifier to the length of all of the ticks to maintain an average load on the servers responsible for running the calculations for the actions in that system.

To fully answer this, you may have to explain what you mean by "soft turn-based." I'm not familiar with the term.

In a traditional turn-based game, you take one or more actions and then you have to wait for the opponent to take one or more actions before you can react. Some games, particularly online ones extend this to give the players a time limit, after which their turn is skipped. This still basically feels turn based.

However, when you start talking about "ticks," (note: many programmers will call these "frames" even when no graphics are involved) you have shrunk the time limit so small that the lines become considerably blurry. Taken to an extreme, FPS games consist of a series of ticks or turns that are usually between 10 and 20 milliseconds in length. In theory it would be possible to process your actions and an opponent's actions on separate threads, but in practice that never actually happens. All the actions for players in a location are processed sequentially. If you press a button during your 20 ms turn, then you fire or move during that turn. If not, your turn gets skipped.

EVE Online, as well as pretty much every other MMO I know about, are all based on this model to some degree. You do not have to wait for other players to act in order for you to get a "turn," but the server is always sequentially processing the inputs it gets in a generally first-come-first-served fashion. EVE is particularly notable in that 1. the developers are more open than most companies in talking about their technology and 2. the duration of "ticks" is variable in order to compensate for high player density that would normally be too much for the server to handle. But it's still generally following the same model that almost all MMOs do.

I guess whether or not you feel that "counts" as turned based is up to you. :)