I thought about finishing our basement and turning it into a man cave last year, but a friend of mine suggested putting down a radon test kit first. It turned out positive for radon, so I went online and got as much advice on DIY radon gas removal as I could. I discovered I had some serious cracks in the basement floor, so that was probably the source for the gas. I had to patch all of those cracks before I could move onto the next steps.
I found a schematic drawing that showed how to drill a hole in the basement floor and run a ventilation pipe into the ground. I bought a ventilation fan at the hardware store and some HVAC tubing to direct the air through an open window. It took a while for the tests to come up negative for radon, but they finally did. I gave up on the idea of a man cave, but the basement does work as a laundry room.