It looks like ya'll made an assumption that he was asking about a simultaneous game.
Turn base games can be played via PBEM as well. It is different and can be longer. A Turn based games starts out similarly. All players send the emp files to the first player. This player creates the game and plays the first turn. Then the turn files is passed from player to player as each plays his/her turn.
Turn based email however is more prone to a slow down in that if one players delays the game the whole game can be delayed. Also turn based breaks down more, the more people involved. If there are 10 people in a Turn based you might get to the point of having one turn a week if every one takes a full day to do their turn.
Don't get me wrong. Turn-based is viable for PBEM. I am playing both styles in PBEM settings right now and find that it is two different flavors of the same game. It takes a bit longer to do some stuff (game time) in simultaneous games.
No combat is strategic only. However you do get to move your ships see the results and move again. So for things like unknown warp points, you get to go through it and see what is there and then leave or go to another planet or warp point on the same turn if you want. And you can do multiple attacks or colonize and build on the same turn or other things that simultaneous forces you to wait to the end of the turn to find out.
Yes I forgot that. If you are using a custom race you need to send that along for the host to distribute or send it to all the players ahead of time. (I have been using one of the default races so I only needed to send the .emp file.)