How to convert this very simple .htaccess to Nginx?

I'm using this .htaccess that pass everything after URL to $param, so example.com/news/id goes to PHP as $_GET['param']='news/id'. But Nginx is always throwing me to 404 page.

My .htaccess:

RewriteEngine On
RewriteCond %{SCRIPT_FILENAME} !-f
RewriteCond %{SCRIPT_FILENAME} !-d
RewriteRule  (.*) index.php?param=$1

What I tried in Nginx default.conf:

server {
        listen 80;
        listen [::]:80;
    server_name domain.com;
        root    /var/www/html;

        location / {
                if (!-f $uri){
                        set $rule_0 1$rule_0;
                }
                if (!-d $uri){
                        set $rule_0 2$rule_0;
                }
                if ($rule_0 = "21"){
                rewrite ^(.*) index.php?param=$1;
                }
        }
}

You don't use if here at all, nor do you manually check for the existence of files. This common pattern is handled instead by try_files.

For example:

location / {
    try_files $uri $uri/ /index.php?param=$uri;
}

(If your web app is broken and can't handle the leading / in the URI, fix the web app if possible, or see this question if not.)

I could fix it using these rules:

server{
try_files $uri $uri/ @rewrite;
  location @rewrite {
  rewrite ^/(.*)$ /index.php?_url=$1;
  }
}

If you have location / { } without any instructions inside, remove it.