As late Gen X I grew up without internet, and my parents both grew up on rural farms and were quite frugal, so we didn't have cable TV, air conditioning, or much of anything else.

I spent a lot of time reading (fiction and encyclopedias), bicycling, building tree forts in the woods, snow forts, swimming (city pool or nearby creek that was probably full of mildly toxic runoff), building stuff (lots of Lego creations), etc. There were arcades, but it took like two hours on the bus to get there and then you need money to play, so that kind of sucked. We almost never had any money, so we very rarely did anything that wasn't free. Spent a lot of time at the local library in the summer (probably read half of the scifi/fantasy section by the time I got out of high school).

About once a month on a Friday night we'd go to the local video rental store and rent a couple of VHS movies and a VCR so we could watch a movie. Eventually they also offered rentals of a NES machine, so we could play a video game at home.

We always had a home computer though, so sometimes I'd play simple games on the computer. Then when I got bored with the games (which didn't take very long since they were all free stuff from the early days of computers) I'd go through the source code for them to learn to make my own. From about middle school on I spent a lot of time programming (with a few sample programs and lots of time as my only resources).