My garage is my game room, and we get colder in the winter, and around the same in the summer. I have never had any issues with the games, but it is a pretty extreme temperature change. I started heating and cooling my garage one I started buying more expensive games, and I try to keep it between 60 and 75 at all times now. If I had space in the house for games, I would put the expensive ones inside, and save the money in the garage.

Again, I never had any issues n I wasn't controlling the temps, but I want to keep the nice games nice just in case. It is also really nice to have the garage comfortable for me whenever I decide to go out there.

I am only using a $700 portable unit from Costco, and it works pretty well. It costs me about $50/month to run it. It would be cheaper, and most likely better use a mini split system, but the upfront cost was about 5 times as much, and we plan on buying a bigger house with space for an inside game room in a couple of years, so it didn't make sense to install one here.

I insulated the walls, and sheetrocked the whole garage. I was planning to blow in insulation in the rafters, but I haven't managed to get it done yet. I had to put in a good seal at the bottom of the garage door because there was a big enough gap that water came in when it rained.

You both are West Coasters, like me. Less humidity. I read somewhere that HUMID temperature changes were far worse than dry temperature changes. The day to night swing in temperatures is greater in our "desert" climate but no/low humidity, so not so bad.

I put a Mini-Split A/C and heater in my garage to keep it climate controlled. It runs 24/7 to make sure that the humidity is controlled as well.

I did insulate my garage door using two of these kits: http://insulation.owenscorning.com/homeowners/renovation/products/garage-door-insulation-kit-accessory/

Lots of people out here with games in garages year round. Not a terribly big deal.

Not so much up here in Canada.