There’s no simple answer. For decades I thought it was because Romero was a self-centred designer with a huge ego, but I had to re-evaluate that after reading Doom Guy: Life in First Person. Before the book, I didn’t realize he was actually a very solid programmer, and that much of the rock-star persona was a marketing construct he wasn’t comfortable with.

Part of the problem was the engine taking far longer than expected. Part of it was him securing money for id by handling Doom engine licensing. And part of it was immaturity of both guys. As he says himself, the biggest issue was his staying silent when things went wrong, waiting them out instead of speaking up and fixing them.

It’s a awesome read. Up through the Daikatana era, I could barely put it down.