In the Web version of iGap there are many features as in other versions. One of the most important of them is to have your own room as a channel and even in public. It means that you do not need to add members to increase the number, all iGap users can join it easily and use the shared media. Do not forget, your public channel needs a username or an ID, so others can join it by clicking.
In iGap app, also you can have groups in private or public, but you can convert them private to public or vice versa and apply new possibilities. Remember, in order to have a public group, you have to create a private at first. Then by converting to a public one, and adding new and/or unknown members get familiar with more iGap users.