Your browser does not seem to support JavaScript. As a result, your viewing experience will be diminished, and you have been placed in read-only mode.
Please download a browser that supports JavaScript, or enable it if it's disabled (i.e. NoScript).
Can this be done? If so, how? (Closed game before adding).
If you click on your Game History (column in blue down the left of screen), you should see that game at or near the top of the list. Each game played has a green ‘Collections’ tab on the right. You can add it that way.