That's ok, this topic can be moved. It is game related and forum related so it can either go in the Game Discussion or the Forum Questions Suggestions And Requests.
As for finding or marking the games you liked or played from here, sorry that isn't possible with this forum software.
However...
If you haven't noticed already, there is a voting system on each post. On the far right hand side of each post there is a small
+ and small
- symbol. This is the voting system. You can use this if you like to mark posts/comments/games as useful or not useful but you will need to remember that it's there as it's easy to miss. If you vote
+, that is a positive vote and will mark it as a small green vertical bar. If you vote
-, that is a negative vote and will mark it as a small red vertical bar. These votes also go towards your forum Points and your forum Reputation. You can only vote once on each post and you can not vote on your own posts.
You can also search for the name of the game, topic or author from the forum search box up the top of the page.
Unfortunately there is no other way to view the games you've already viewed or played apart from what you have already mentioned... and that is bookmarking or marking them as favorites in your web browser. I would recommend making a folder for all your favorites as this is the easiest way.
Hope this helps