You can't really have a 'basic metric'. Let's say we all agree we all game. Great. Someone plays a bunch of 2d games(Undertale, etc), someone else plays classic 3d games(Deus Ex, Half Life 2, etc), someone else plays newer games like GTA V, someone else plays bleeding edge games like Assassin's Creed Origins.
How do you devise one metric that serves them all equally, when things like settings/ram/videocard all can affect performance AND affect performance differently for each person?
The best way to get help to choose a CPU is simply to specify your needs. "I want to play X game at 1080p high settings" and then people can suggest the CPUs that would allow that.