I’ve done this a couple of times. This isn’t about Regina but the drive there. I would recommend taking Hwy 3/CrowsNest. After Medicine Hat you’re on Hwy #1 any way. A wonderful trip though southern BC and Alberta. AS far as the game goes, Go to the bathroom before because the line-ups can be bad. Not like the Dome. And wear your Lions Jersey with Pride. A good time is almost guaranteed.
Park at one of the several locations away from the stadium and take the free shuttle bus. The one we use is next to a Montanas, so we are all full when we get to the game. Concessions are much cheaper that way.
Don’t be shy about talking to people. Strangers will engage with you as if you’ve known them for ages. Especially if you wear green and have a modicum of football knowledge.