Yes, there is a filter to browse games by status. It's not an issue of programming anyway. The question is, who gets to decide that a game is abandoned as opposed to simply finished? Based on what?
Viewing post in *Feature Idea* Flagging abandoned projects
I may have misunderstood your question actually. If so I apologize. The only other way I could think of answering it would be the developer. The one's actually responsible for the project would have a clear idea about what scope they want for their work. Once they are satisfied with their work, and feel it is complete, the developer would be responsible for marking it as completed. At which point the flag as abandoned feature could be permanently disabled on that particular project.