With the rapid growth of the gaming industry, real-time online multiplayer games have surged in popularity, driving an increasing demand for the development of complex software. In particular, game developers often face significant challenges when working with networked code (netcode). The design space of available netcode libraries is large, yet there is limited guidance when implementing an online multiplayer game. To compensate, we present a catalog of netcode patterns providing guidance when implementing real-time strategy and role-playing games. We use two concrete games serving as case studies for pattern identification and validation.