Looking for ideas on ways to help my pup get rid of his winter boredem blues l.

Looking new ideas to tire my little guy out mentally and physically that can be done in our house …his bored groans are killing me!!!. So Barney is my 12 year old Dachshund and the light of my life!!! He still plays like a puppy, loves his Stuffies, puzzles , treats balls etc and with 3 acres and ample walking trails keeping him happy is a breeze for most of the year until the peak of winter hits and ours trails have three feet of snow on them and our sidewalkless roads have 10 foot snowbanks and cold slush that reachs up to my poor boys belly!! We snowed in literaly!!! Luckily my husband deligiently snowblows are large patio plus a generous section of our backyard for Barney to do his business in comfort but besides a few loud barks just to let everyone know this is his yard he back inside like a flash. I play with him as much as I can, he has an emabrsssingly large selection of toys, puzzles, chew sticks etc and yet I'm constantly being stared down with his beady little eyes and guilted with overdramtic sighs that could rival most teenage girls (has anyone who's ever had a dachshund kind of test they are drama queens). And I feel bad for him I get it he's bored silly being cooped up inside and so I thought I'm sure there must be tons of enrrichment ideas I haven't thought of to get my little guy out of his funk. Please Help!!!