Multiplayer is done very badly in this game, a shame since it wouldnt take much to fix it.
First of all, the lobby and game creation is abysmal, like, really really bad. Then there is the whole connection problems and resyncs, disconnects and random crashes....but really its not unplayable, its just not as good as it could be.
Simul tourns well, in FFA Games which most play its the only option, because otherwise games just take too long (imagine 5 players taking turns). However, if you are new to the game, or your opponent is simply very good at *abusing* the mechanics, you have absolutely no chance of winning.
We are talking *losing everything and killing nothing* here. Its entirely possible to save every low HP unit and killing of every unit of your opponent if you abuse the shift click mechanics and the end of turn movements and using your units faster and using promotions faster than your opponent, its really that bad.
Watch out for these things:
1. Shift Movement. Pretty much nothing you can do here, your opponent moves between turns to close distance into your defense, or to move cav next to your units from 4 tiles away, attacking and moving away with it, hope you have high frustration resistance. Be prepared to lose workers to units (especially scouts) you didnt even know are there, they can shift move out of fog of war and steal your worker/pillage without you having any chance of saving them. If you know other players are in that general direction, always escort them.
2.End of Turn Movements: this is really a dumb thing but its done very often. Essentially people will let the turn timer run down to the last second and move their units in that last second so that you cannot react to that movement (even with shift clicking). this really sucks because not only is it highly advantageous, but also does it make turns take A LOT longer because every turn is run down to the last second. A good example of this is Archers moving 1 tile and shooting to get essentially a free attack of on you or declaring war in the last second and stealing workers/attacking settlers/killing units the next turn.
3. The *Bait*: VERY Common. What happens is that you move a unit in range of your opponents units (2 tiles away), best done out of fog of war for maximum effectiveness. Now your unit has 1 movement left, but your opponent doesnt know that, or he could know but doesnt have the time to think it trough (have to react very fast in simul games). Now your opponent can essentially attack it, but because they have to move fast they will attack by moving their unit onto yours most of the time even with ranged units. Now you know he will attack it, and you just wait 2 seconds and move your unit BACK 1 tile and your opponent unit will MOVE into the tile instead of attacking. This will almost outright kill the unit most of the time since its out in the open without defenses. You can also just move a unit 1 tile forth and then immidiately back and your opponent will try to attack it but cant stop the motion anymore and move his unit instead. This is one of the most frustrating things in the game.
4. Faster movement: This is why i say *lose everything kill nothing*. You opponent has a low HP unit, you try to finish it off but he moves away, your unit moves on the tile. Both players have a low unit, but he shoots faster and kills your before you can move it away/shoot, you lose the unit. You have a promotion but before you can take the bonus HP he kills your unit cause he clicked faster. you have a general and want to create a fortress but he kills all units on the tile before you can do it. You want to recapture a worker but he can dismantle it before you can move on the tile. The list goes on and on.
Now the problem is that this doesnt just happen once, if your opponent is faster he generally is ALWAYS faster. So you lose all low units, he saves all low units, he gets all his promotions you get none, he captures your workers but you cant capture his, he settles first so you settler cant settle anymore etc. etc.
Fortunately outside of leagues, there are not that many players that can abuse it this well (me and my friends can, so we stopped playing simul entirely, its just way to much abuse and no fun at all). Now i wish that Turn based has been done better, cause that sucks as well. You cant give commands while its not your turn, cant change production, cant even open civilopedia or any other menu, its horrible.