I have been watching a lot of game development coding tutorials over the last couple of years. This includes things like the excellent Game Developers Conference (GDC), Sebastian Lague and his wonderful coding adventures series, and Yahtzee's dev diary series to name a few.
It's difficult to not see developers use Unity when demonstrating their game developing online. Some developers will directly reference it, whilst others will simply look at the code they are writing. Unity, though, didn't appeal to me as it comes with some licensing costs. You only need to pay those licensing costs if you release a game, but as a hobby developer who advocates free and open source development Unity just didn't sit well with me.