gistfile1.txt

#routes.rb
new_game_topic_post GET    /games/:game_id/topics/:topic_id/posts/new(.:format)      {:action=>"new", :controller=>"posts"}

==========
#posts/show.html.erb
<%=h @topic.name %>
  <table>  
    <tr>  
      <th width="60%">post Title</th>  
      <th width="10%">Replies</th>  
      <th width="30%">Last Post</th>  
    </tr>  
    <% @topic.posts.each do |post| %>  
      <tr>  
        <td>test</td>  
        <td>%= post.posts.count - 1 %></td>  
        <td class="right"></td>  
        <td></td>  
        <td><%= link_to "Edit", edit_post_path(@topic.id) %></td>  
      </tr>  
    <% end %>  
  </table>  
    
<p><%= link_to "New post", new_game_topic_post_path(@post, @topic) %></p>

===========
#posts_controller.rb

  def new
    @post = Post.new
    @post.pic.game_id = params[:topic][:game_id]
    @post.topic_id = params[:post][:topic_id]
  end

==========
#ERROR:

New Posts link is generating: 
  /games//topics/23/posts/new 
instead of 
  /games/1/topics/23/posts/new 

thus:
No route matches "/games//topics/23/posts/new" with {:method=>:get}