New members of this site have some light restrictions on how many games they can join or create at once. You need to play at least 20 phases, before you can join more than 2 games, 50 phases, before you can join more than 4 games and at least 100 phases, before you can join more than 7 games at once. 2-player variants and private games are not affected by this restriction.
You can see your total phases played and more useful information in the reliability section of your stats page.
The restrictions are in place to ensure all new members do not jump into more games then they can handle. Diplomacy games can take up a lot of time so please test out several games before committing to multiple.
PLEASE NOTE: If you fail to submit orders for your country and used up all the excuses you have for the misses in the game the country is sent into "Civil disorder" which allows any site member to take over your position to ensure that the game's integrity is not negatively impacted.
If you have too many unexcused missed turns within a year you will be temporary banned for a short period and you will be restricted in the number of games you can play (2-player variants and private games excluded). This is to ensure that all players take care not to take on more games then they can keep up with, and to ensure that players who do not respect their fellow members are not given the chance to ruin multiple games.
If you were unreliable and due to that received some game limits and do not want to wait for a year until the record has lapsed you can increase the number of games you can join by taking over open spots in ongoing games. Each take-over will compensate one unexcused miss and will so reduce the game limits you experience.
You can read more about the specific sanctions for unexcused misses here.