Here is game that a long time would have looked on one of those early computers in the eighties. However, it may have the looked of a classic game, but when I checked there were sixty other players on there. It is a bit of fun that is easy to play, chat and even fight if you choose.
According to the posting on the Mozilla blog, Paul Rouget HTML5 specialist and Firefox engineer said;
BrowserQuest can be played by thousands of simultaneous players, distributed across different instances of the in-game world. Click on the population counter at any time to know exactly how many total players are currently online. Players can see and interact with each other by using an in-game chat system. They can also team up and fight enemies together.
Source [Browser Quest]