Only recently, my 1½ year old females cat have been playing "soccer" with a dry food morsel across the kitchen and then returns to the bowl to eat. Why do they play with their food? Are they bored of the particular type of dry food I'm giving them? Do they need me to play with them more?
It's just their play/hunt instinct kicking in. The piece of food might have dropped outside the bowl, cat uses a paw to get it free (to take it), then notices "omgosh! it's moving!" and starts to "hunt" the food.
Nothing abnormal here and I wouldn't expect this to be just due to the cat being bored. Especially if the other cat sees the hunt, it will join in, no matter what the original cat is after.
You can always try to play more with cats, but I honestly think that this is just coincidence due to the food ball moving the right moment (for whatever reason and unless this really happens consistently).
I actually use this hunt/play behavior to get my cat to exercise. I toss a piece of food down a long linoleum floored hallway, and she chases it down the hallway (playing soccer with it as she goes), until she catches and eats it. When she returns to me for more food, I toss the next piece down the hallway.
I think of it as a kitty pinball game, with the gap under the closet acting as the bottom of the pinball game between the flippers where you lose your ball. After the game, my cat tries to fish food out from the closet until I open it and let her reclaim her lost food.
Do you guys have any other cat toys around? If not, then they're playing with stuff because they don't have anything else to play with.
When they get bored enough, they will start to bring you little gifts - just to show that they love you - and to ask you to play!