The sl.Gamelauncher is a little and useful tool, to connect to a gameserver directly with your favorite webbrowser. The newest version is currently 0.65, you can download it here.
Install the sl.Gamelauncher into a directory you like.
Here's a screenshot from the sl.Gamelauncher and all supported games.
right-click onto your game, a menu should now appear you select "search location" to search for the game binary (for example: ET.exe)
last but not least, you have to bind the game into your browser. You can do that if you right-click on the game, and select "bind to browser", or you just tick the checkbox on the left side on.
Now you can close the window, and can connect any server via "Connect" Button