You can play 1 vs. 1, 2 vs. 2, 3 vs. 3, etc. depending upon the size of the camp. The maximum number of players is posted at each camp (also known as "map").
The same match games apply as registered teams.
First, you must be a member of a Registered Team. Go to "Teams" forum http://infdat.com/forum/viewforum.php?f=4" onclick="window.open(this.href);return false;
to either form a team, or join a team. You need to have at least 500 frags to join or form a team. Look through the forum or ask around in camps for other players looking for a member or looking to form a new team.
If you are forming a new team, you'll need a total of 4 members. Post the desired team name and names of the members on the forum. Have each other member confirm his/her desire to join said team on the same topic.
