RewriteEngine on 
RewriteCond %{REQUEST_FILENAME} !-d 
RewriteCond %{REQUEST_FILENAME}\.html -f 
RewriteRule ^(.*)$ $1.html

Options -Indexes

ErrorDocument 404 https://gelgaming.com/
ErrorDocument 403 https://gelgaming.com/

RewriteEngine On 
RewriteCond %{HTTP_HOST} ^gelgaming\.com [NC]
RewriteCond %{SERVER_PORT} 80 
RewriteRule ^(.*)$ https://www.gelgaming.com/$1 [R,L]