Walk in and immediately go up the steps to the third floor. Once there, go to the southeast corner of the building. DO NOT cross through the gym. It's room 316. The door says "STRATEGIC GAMES SOCIETY" in big letters on the door, but more commonly the door will be open.
We have a broad selection of games of all types and descriptions. You're most likely to find someone to play a multiplayer game taking three or 4 hours, like Titan. Just come by and start suggesting things from the shelf,or bring your own games, since most people are eager to learn new games.
The two maps below show Walker Memorial highlighted in blue in increasing detail.
Another map of MIT with building 50 highlighted.