The MIT is, but GPL is actually very restrictive. For example, it disallows publishing derivative works without those being licensed under the same terms (or newer GPL versions). That’s why commercial companies are reluctant to use GPL-licensed code in their products.

Someone said a beautiful thing on the internet: think of playing a game like visiting a friend. You casually pop by as often as you feel like it. Some friends are really once-a-year material.

I recently picked up Derail Valley after an 8-month hiatus, and almost doubled my hours in that game over the course of two weeks (it was a lot of playing). I just felt like it.

Just FYI, most open source software is not in public domain, it is protected by the same copyright we are talking about here, except the author made it available under certain conditions (the licence).