If I understand correctly, the problem is the server is simply overwhelmed with active games, including games where everyone has left. There are undoubtedly a very large number of Baal games that are played, so attention to them should be considered.
Why not make the server immediately terminate games when everyone leaves where Baal has been killed? This would eliminate a significant amount of games the server continues to run for a period of time after everyone leaves, freeing up available game creation slots.
This would not affect mule games, that is as long as the muler doesn’t go and kill Baal.
If one is running an average of 3 minute Baal games and the server continues to run vacant games for 5 minutes after leaving, a single player can have a trail of 1 to 2 vacant games running on the server in addition to the game they are running. That is if they are trying to stay at or under the 20 games/hour limitation to avoid restrictions. The problem gets worse when the ahem player is switching their CD keys in order to do faster runs, then the trail of vacant games grows even longer.
Just throwing this out there in case it hasn’t been thought of. Being one who solves problems for a living, I know the simplest solutions can be easily overlooked. The idea sounds simple enough, however I have no clue how easy or difficult it would be to implement.
If a Blizzard rep happens to read this, all I ask is that you forward this to the classic team to see if it’s able to be done.