Back Them into a Corner
When you're confronting an enemy, it's immensely useful to know and thoroughly understand the enemy's weak spots. In the early '80s, Super Mario Brothers fans quickly learned to jump up and land squarely on the bad guys' heads. Pro athletes study their opponents' patterns and try to catch them by surprise. Goofy examples, for sure, but they do offer some real-world guidance. Dealing with a pest infestation at home feels pretty real-world, and in the case of mice, a common townhouse pest, this might simply mean accepting that there are no limitations.
Not to get all discouraging, but think about it. They're small and quick. They're fast breeders and like to share their new digs with the whole clan. They hide easily. And, perhaps most of all, they're dirty and destructive little thieves.
Townhouses pose some interesting dynamics in a mouse infestation because, given enough time, mice can chew through anything. That includes your walls, especially if your complex was constructed kind of cheaply. The space between your rec room and your neighbor's is probably a few inches of darkness crammed between some 2x4s, a little insulation and some drywall. Drywall is easy for a mouse to nibble its way through. Beams and framing are excellent for climbing and navigating. Insulation fibers are prime nest-making material (reassure yourself, if you can, that the poor mouse might suffer from some nasty respiratory infections...which is only fair if they're stealing your insulation). So imagine a mouse (or several) living happily in the void between you and the adjacent townhouse and they occasionally head out to scavenge. Your neighbors notice some mouse feces, or find some chew marks along the baseboards or hear scurries in the night. They decide to put out traps, or maybe even some poison. The mice retreat back to the nest and wait as long as they can, but in a couple days they need food again. They'll go back to your neighbors' place if they get desperate enough, but not yet. There's a hole in the baseboard that one of them can poke its nose through. And mice have squishy little bodies and weird little skeletons. They can squeeze through any hole they can get a nose into -- and now your kitchen is theirs.
So keep your food sealed in heavy-duty containers and throw your garbage away frequently. Make sure your pets' food isn't scattered across the floor. And if you see any holes in the walls, baseboard, closets, garage or wherever, seal them up as fast as you can. Use a metal mesh drywall patch. Pack it well. A mouse will just poke its nose right through a sloppy repair job. Talk to your neighbors and formulate a joint plan of attack. Traps or more drastic measures will work better if you get the mice cornered on all sides.
If all else fails, just get a cat (but watch out for mites).