Actually, if we're going for species-specific enrichment, a pumpkin may not be the best solution. We're not built for pouncing on prey or batting it around. We're distinguished by our persistence hunting and tool use
What you should do is put a pack of jerky on top of a roomba, go in another room and count to ten like you're playing hide and seek - or use this time to find a tool to use - and when you come back, try to catch it by setting a trap or by pinning it down with a stick
When you want a greater challenge, have a friend drive an RC car full of jerky around the park, and chase it until it runs out of battery