cat wants to play, but won't

Since getting my kitten Tails (4 months), my other cat Memphis (1 1/2 years) has all but stopped playing with me entirely. Whenever I play with Tails using Da Bird, Memphis will watch from the hallway, or from the kitchen, very intently. He watches every move the feather makes, and he looks like he is going to pounce. Only, the second Tails makes any move whatsoever, Memphis backs away and becomes an observer for the entire time I'm playing with Tails.

I tried breaking him of this by not playing with him otherwise, but this did nothing to encourage him. I tried adding a second Da Bird to playtime, but Memphis is more preoccupied watching Tails go after his feather than he is in attacking his own feather. I started locking Tails in my roommate's room across the apartment so I could play with Memphis uninterrupted, and this works for at most 3 minutes. The second Tails starts to meow to be let out, Memphis loses all interest in playing, and runs to investigate. It is literally impossible for me to play with Memphis, but I can tell he wants to. He'll sprint up and down my hallway for an hour, and sometimes he'll go to the closet where Da Bird is and scratch at it and look at me. I get it out, he pounces a few times, Tails hears it and comes running, and Memphis is done. It doesn't help that Tails will run to the feather even if he is exhausted. He'll go up to it and lay on it so I can't continue playing with Memphis, so I have absolutely no idea what to do to get Memphis some more interactive playing.

Has anyone else dealt with a cat who refuses to play and chase things around with another cat present? Am I stuck with one neglected cat until my kitten gets some manners and learns some restraint, or what?

I tried that for a while, and it worked fractionally. The problem is Memphis and Tails have opposite play styles; Memphis stalks and pounces while Tails chases anything that moves. So Memphis is watching his feather, waiting for it to land so he can pounce, but Tails sees movement on his feather and runs after it, distracting Memphis.

I'll try getting another laser pointer. Memphis never liked it when he was alone here, but he would chase it for a couple minutes at least since Tails got here. Unfortunately, I started carrying it around everywhere so I could play with the cats immediately whenever I wanted, and being a 23 year old grad student, I didn't check my pockets before doing laundry...

I thought I'd update you guys, because we had a major breakthrough tonight!

The breakthrough started on a down note: the feathers on Da Bird completely ripped off down to the nub. So I take the nub off the little metal clasp to put the spare feather on, when all of a sudden Tails lunges at the metal clasp. I jerked it away quick since it was still open and I didn't want to go fishing for kitties, and he lunged after it again. So I close the clasp and start dragging it across the floor, and Tails going way crazier than he ever did WITH the feather . I thought that was where the good times ended, but apparently Memphis is an aural-stimulus cat, because he heard the metal-on-floor action and jumped straight from the top of the fridge to the floor, without using the counter per usual. He then proceeded to chase the string with fervor, actually meowing in excitement (he had NEVER chattered while playing, even before Tails came).

Both cats were panting by the end of 20 minutes, which is also very rare. With this level of excitement I think the feather is staying off Da Bird, at least for now