As I've passed 40 years old I tend to find that I've slowed down and unless I do a hard cardio program for a few months like P90X then I cannot keep up with the young guys at BJJ. I see a lot of the younger men at the club depending on scrambles and quick movements but there is a lot of energy and athleticism required for that type of jiu-jitsu. I love watching it, don't get me wrong but I cannot sustain such a pace for long periods of time.
The more I think about the best old man's game, I tend to come back to certain aspects that are best suited to ensure that I don't get injured and I can continue to spar with younger guys at least for another couple of decades.
1. A guard based on anything that will keep them off my neck and their weight off me.
Butterfly guard, X-guard, Knee-shield
Lots of framing with straight arm and elbows to prevent passes
2. A passing game that is slow with lots of pressure and requires more use of correct body weight and less physical strength or speed.
3. Takedowns that cannot be countered easily with a throw, no head first takedowns like single/double leg, takedowns used to counter single/double legs and after grip breaks
Sacrifice throws such as sumi-gaeshi and tomoe-nage
Pulling down into butterfly sweep
Collar drag and arm drag
For now, this seems to be the best way for me to do jiu-jitsu to prevent injury and prolong longevity in the sport.