To run Traq on Nginx you will need to configure your server to use Traq's index.php as one of the URL's to try, which means you will need access to your virtual host configuration file.

You, or your host, will need to place the below configuration, or a similar one, inside the server block of your configuration file.

location / {
    try_files $uri $uri/ @rewrite;

location @rewrite {
    rewrite ^(.*)$ /index.php;

Note: This configuration assumes Traq is setup in the root of a subdomain.