Freeciv.net - multiplayer strategy game playable online with a HTML5 browser
About The Freeciv.net project:
Freeciv.net is an open-source turn-based strategy game. It’s built entirely in HTML5 and features in-depth game-play and a wide variety of game modes and options. Your goal is to build cities, collect resources, organize your government, and build an army, with the ultimate goal of creating the best civilization. You can play online against other players (multiplayer) or play by yourself against the computer.