Please, if you want to download it, download "Serpens Ruby.zip", the first version weh uploaded has the svn files and extra files that are no neeeded to play it.
It's an HTML5 game, should run fine in a web browser. Ruby has to collect as much gems as she can, if she misses gems, the snake will eat them and its tail will grow up, when the tail reaches the head, the game is over. Use the arrows to move and jump.