Unity is great for a certain class of games. But I've played plenty of games that were developed with Unity, where the dev quite obviously strong-armed the eng

Unity is great for a certain class of games. But I've played plenty of games that were developed with Unity, where the dev quite obviously strong-armed the engine into doing what they wanted, and what you end up with is a slow, stuttering game that would likely run 10X better if they had used a different engine, or even just a renderer with some middle-ware. Also, think of the most successful indie game ever made (Minecraft). It was written in Java (a much maligned language, wrongfully IMO), with a very thin framework (Lwjgl), and it's made its creator a billionaire. If you're doing a game in a relatively mature genre, then yes, engines are great and will save you a ton of time. However if you want to do something completely outside the box, sometimes you save a lot of headache by just simply writing it yourself.