Following a positive fan reaction to BioShock Infinite's 1999 Mode, developer Irrational Games announced today that an even more challenging "1998 Mode" will be offered for upcoming expansion Burial at Sea - Episode 2, which launches for Xbox 360 and PlayStation 3 on March 25.

"In Burial at Sea--Episode Two we put a focus on balance and stealth mechanics," Irrational Games creative director Ken Levine said in a statement. "As we were developing this new style of gameplay, we started to see people self-impose non-lethal playthroughs. Given the fan reception of 1999 Mode, we thought it would be cool to give them another way to play Burial at Sea that challenged their mastery of stealth tools."

The 1999 Mode, as you can see in the image above, is inspired by the stealth series Thief (which originally launched in 1998) and challenges players to complete the content without killing anyone.

Burial at Sea - Episode 2 is set in the original BioShock's underwater city of Rapture and puts players into the shoes of Elizabeth. It follows Burial at Sea - Episode 2, which GameSpot scored a 5/10, with reviewer Kevin VanOrd saying: "Burial at Sea seems a prime example of the tail wagging the dog, and the result is an adventure with fantastic sights and sounds that don't come together in a meaningful way."

Last week, Levine surprised many when he announced that Irrational Games was "winding down," meaning all but 15 staffers had lost their jobs. Levine is working on a "smaller, more entrepreneurial" project for Take-Two with those remaining at the company.