I just found an interesting plugin wp trivia game, the plugin for question and answer game.
It’s may be a nice plugin for wordpress developed by me that allows you to post tag to a wordpress post from comment to that post.
Here are three images shows the step how it works.
Step 1: comment submit
Step 2: after submitted comment
Step 3: After approved by admin
May be it helps you to make post better for adding keyword. Enjoy…..