How to write a php online game similar to Travian? What is required is knowledge of programming? How the programmed events in the game?
It 's like asking "how to build a tank? What tools do I need? Should I know about metals and wheels?" You need to know a server side language (php, python, java), a front-end language (javascript, flash) and the general concepts of programming.
If you really knew PHP you shouldn't have had to create the topic. Looking at that site, you'd need to be quite knowledgeable in HTML/CSS/Javascript/PHP/Drawing (as its quite heavy on the illustrations).