[phendrenad2]

Note that this is primarily about 2D indie games. For 3D, it's not much of a question, you probably need an engine.

[cyber_kinetist]

If you throw away photorealism and limit yourself to stylized 3D, using a custom engine can certainly be a pragmatic choice.

The best examples I can think of are Thumper, Devil Daggers, Hyper Demon, The Witness, and No Man's Sky. And of course, Minecraft!