thank you jon ;) it works now !

Jon everything works fine besides one little issue. I successfully installed second wordpress : www.gungameshub.com/articles. Custom permalinks work fine on the main website. Default plain permalinks work fine on gungameshub.com/articles, but when I change from default to custom permalink (/game/%postname%/) and when I try to access link like gungameshub.com/articles/game/example-post I get 404 Sorry, the search is not found! (that 404 page has main website’s design, so I doubt that custom permalinks are looked up under main wordpress, not the second one(/articles)). Do I have to modify nginx server block? Everything works fine, just this is left.

Main site is placed here: /var/www/html
Article`s site is placed here /var/www/html/articles
This is my nginx server block:

server {
    listen 80;
    server_name www.gungameshub.com gungameshub.com;
    rewrite ^/(.*) https://www.gungameshub.com/$1 permanent;
}

server {
    listen 443 default_server ssl;
    listen [::]:80 default_server ipv6only=on;

    root /var/www/html;
    index index.php index.html index.htm;

    server_name www.gungamehub.com;

    ssl on;

    ssl_certificate www.gungameshub.com.chained.crt;
    ssl_certificate_key www.gungameshub.com.key;

    ssl_protocols TLSv1 TLSv1.1 TLSv1.2;
    ssl_prefer_server_ciphers on;
    ssl_ciphers 'EECDH+AESGCM:EDH+AESGCM:AES256+EECDH:AES256+EDH';

    #block user agent bots
    include /etc/nginx/block.conf;

    set $cache_uri $request_uri;

    # POST requests and urls with a query string should always go to PHP
    if ($request_method = POST) {
        set $cache_uri 'null cache';
    }
    if ($query_string != "") {
        set $cache_uri 'null cache';
    }

    # Don't cache uris containing the following segments
    if ($request_uri ~* "(/wp-admin/|/xmlrpc.php|/wp-(app|cron|login|register|mail).php|wp-.*.php|/feed/|index.php|wp-comments-popup.php|wp-links-opml.php|wp-locations.php|sitemap(_index)?.xml|[a-z0-9_-]+-sitemap([0-9]+)?.xml)") {
        set $cache_uri 'null cache';
    }

    # Don't use the cache for logged in users or recent commenters
    if ($http_cookie ~* "comment_author|wordpress_[a-f0-9]+|wp-postpass|wordpress_logged_in") {
        set $cache_uri 'null cache';
    }

    # Use cached or actual file if they exists, otherwise pass request to WordPress
    location / {
        try_files /wp-content/cache/supercache/$http_host/$cache_uri/index.html $uri $uri/ /index.php ;
    }

    location ~* \.(js|css|png|jpg|jpeg|gif|ico)$ {
        expires 20y;
        log_not_found off;
    }

    location = /mobile {
        return 301 /m;
    }

    location ~ \.php$ {
        try_files $uri =404;
        fastcgi_split_path_info ^(.+\.php)(/.+)$;
        fastcgi_pass unix:/var/run/php5-fpm.sock;
        fastcgi_index index.php;
        include fastcgi_params;
    }
}