Some collective nouns for people at a rugby game are a team of players, a crowd of patrons, a stadium of fans, a crew of maintenance workers, or a group of vendors.
A group of computer games is a bit modern to have a well established collective noun all its own. Currently, general collective nouns are used, such as a box of computer games, a disc of computer...
A collective noun is used to refer to a group of people or things. The opposite of a collective noun is a countable noun. If I say there is a flock of birds, you really don't know how many I mean...