Generally when you log onto ICO, it will take you to lobby 1.  There are 2 versions of the lobby.  There is the regular sins/entrenchment lobby and the diplomacy lobby.  You can not see entrenchment/vanilla players from the diplo lobby and vice versa.  It will tell you the total amount of players online at the top of the lobby screen.  If you click the join game button, it will tell you how many games are in progress and how many are available to join.  If it is non peak times, it is unlikely you will see many people.  I am not sure about entrenchment/vanilla since I haven't been on it in a while but its likely to have less players at any given time.  Hope this was helpfull.  It helps to have friends added online but that is mitigated by the smurfing that remains rampant on ICO.

[_]-Greyfox