Subcategory Recent Posts in Sidebar code needed

Problem: In the category page, I would like to display the recent posts of all the subcategories in that category, without displaying the recent posts in that category itself.

I would also like to do this with the sidebar in the single post.

Example:

Category: Games
Subcategories: Checkers, Chess, Poker

If I am in the Games Category Page, I would like to see all the recent posts only in the checkers, chess, and poker subcategories, but exclude the posts that are checked as Games.

If I am in a Games Single Post page, I would like the sidebar code to do the same.

But If I am in a subcategory page, or a singple post, I would like to display the recent posts in that subcategory only.

QUESTION: is there a plugin for this, or what code would be needed.

thank you