The phrase "multiplayer aspect" refers to a feature or part of a game or activity that allows multiple people to play or participate together at the same time.
The online multiplayer aspect of GTA IV seemed like more of an after - thought (in my opinion anyways) but I have high hopes for the online experience this time around. (thatvideogameblog.com)
This also translates into the online multiplayer aspect of the games. (reviews2go.com)
There is almost solely a local multiplayer aspect to these games, often between 2 - 4 players. (mattsgameexchange.com)