In 2002, the first demo of what became Bioshock ran on the first Xbox using Unreal Engine 2 and was set in a space station overrun with genetic mutants, not in the underwater city of Rapture.

It’s just one of many interesting tidbits about Bioshock's development and life at Irrational Games told in Simon Parkin’s long feature on Eurogamer. Parkin talked to several former Irrational members, including co-founder Ken Levine, and uncovered both troubling and hilarious stories.

For example, programmer John Abercrombie said that at one point he replaced the grenades of the grenadier enemy with a 3D model of a cat that would explode on contact and called the mode “cat-astrophe.” When management found out, they made him promise not to secretly include it in the game. "I guess they were concerned about the ASPCA or someone getting wind of it and it causing all sorts of media troubles,” he said. “So I just made a video locally and then went on, fixing bugs."

Abercrombie did this to amuse himself during a brutal development crunch, with many late nights and seven-day workweeks that lasted for months.

"The pressure was on to create something that would impress, and our deadline was looming," one of Bioshock’s level designers Jean Paul LeBreton said. "In a level review, there was some discussion of how an AI should be presented in the short demo. Someone mentioned System Shock 2's evasive cyborg ninjas as a reference point. Ken threw his glasses down and yelled: 'I don't want to hear anything about any f***ing cyborg ninjas!'"

Apparently this was just one out of many such incidents that occurred at what was a high pressure environment, but the team comes off as unanimously grateful for their time with Irrational and Levine.

“Ken can be a tough guy to work for sometimes, but he is driven to make his games great and drives his team towards that same goal,” former level designer Paul Hellquist said. “I always aspire to that goal in my work and probably learned that from him."

The full piece, which you can find at Eurogamer, has a lot more interesting stories and offers great insight at the history of Irrational Games, which in February Levine confirmed was shutting down.