How to keep an inside/outside cat amused in winter
Okay. So, we have a cat who currently lives at my other half's house named Monty. He's a big cat who does not get along with the other resident cat, which is fine in the summer because they can avoid each other. But in the winter, it gets COLD here. Minnesota cold - freeze-the-cat's-ears-off very literally cold. So, the cats stay inside. Despite many attempts to make them get along, Monty is a BIG cat (14 pounds healthy weight) and George is a very small, friendly cat. So, Monty really does a number on George unless Monty is put upstairs in Jack's room... Which is not enough space to keep him happy, especially since there isn't anyone there to love him except when Jack comes home from work to sleep.
It just gets flat out too cold for the cats to be outside, especially with nowhere to go. Next year me and my two roommates are renting a duplex instead of staying at the dorms, and I plan on taking Monty over the winter. (both roomies are okay with this). He will have a dog for company, and plenty of people to love him, and cat toys... But does anyone know of some cheap, creative ways to amuse an inside-outside cat who gets confined inside in the winter? I have no problem bringing him out (with supervision) on nice days, but he quickly decides he doesn't like the snow. But he gets so bored inside. I think he'll be mostly fine, with people and a dog (he gets along fine with dogs) and free space and no rival cats, but I'd like to be completely prepared to give him a nice wintering experience with us.
What about things like Catnip? Catgrass? If I give him catgrass, will he eat the rest of the plants in the house? He'll have cat toys. I have a cat tower we made (that's AWESOME) but we'll see if we have space for it. I just want to make sure he's happy over the winter, instead of choosing the freezing -40 weather or being cooped up alone in a single room and miserable.
Just for fun, here are some pictures of when he was cooped by himself in an old trailer on the back of the property. He'd just gotten his shots, and was running a bit of a fever and felt icky, and the vet told us to keep him inside. We didn't have anything to keep him amused since we didn't expect a cat, he just showed up, so he was probably SO bored (first time inside, too) and it was SO nice out. So, he did what any logical bored cat would do... Dug a hole through the door! (AFTER, of course, worming out the window the first time). DISCLAIMER: He is much less destructive now. He's gotten more used to being inside. He still gets bored and yowls about it.