Find the game that you want to post, click 'Tools' at the top of the window, click 'Page Info', Click the tab that says 'Media', and scroll down the list until you see the word 'Embed' in Italics in the column to the right, it should have an ".swf" format, click on it, click save as, type in whatever you want to save it as, and then upload it to your post.

NOTE: I have been to websites where i couldn't find an 'Embed' in that case look for something that says 'Object'