A Look at Blue Ridge's Momentum
As a small assignment for a game networking course at Champlain College, we were tasked to briefly write about a UDP or TCP networked game. The Transmission Control Protocol (TCP) splits up data into manageable chunks and guarantees ordered delivery. The User Datagram Protocol (UDP) is a simplified protocol that does not guarantee delivery. The right protocol should be determined by the game’s specific needs. While it might seem reasonable to mix and match protocols, it appears that trying to mix TCP and UDP can cause packet loss (source).
While I was searching for a game, I stumbled upon an older networked mobile game from 2004 in the Game Developer magazine. The game is called Momentum, and it was built by Blue Ridge for LG and Audiovox mobile phones. Six players network their phones together, and compete to find coins in a shared maze. The game concept was inspired by old arcade games that quickly engage the user.
At the time, real time mobile play was an issue due to the high latency (ping times peaking at almost two seconds). To mitigate the issue, the developers created a “look-ahead mechanism”, which would allow them to determine players movement in advance. With the network limitations of older mobile phones, the chosen protocol became important to the reliability of the game. Initially they chose to use TCP, but this caused drawing and sound glitches while waiting for the packet acknowledgement. To fix this, the developers switched to UDP, which reduced packet overhead and provided a more consistent experience. Since they still needed much of the functionality of TCP (i.e., automatic retries, packet ordering), they had to recreate the functionality.
Over the course of the project, the developers dealt with a numerous other networking, performance, and design hurdles. By the end, Blue Ridge successfully created a game that was well received by the critics. Since the release of Momentum in 2004, there’s been an astonishing change to the mobile industry.
If you’d like to read more about Momentum, see Game Developer magazine’s October 2004 issue.
September 07, 2012