If you'd like to better familiarize yourself with Ken Levine's 15-year development history, you'll want to check out IGN's two-page "Ken Levine and the End of the Auteur" editorial and the accompanying five-minute video interview. A snip from the former:
When it was released in 1999, System Shock 2 exceeded expectations and has come to be looked at more fondly than the original by many. Irrational took the themes of possession, dark violence, and authoritarian corruption and made them a backdrop for a combat game where players could discover new layers of balance and ability through their own upgrades and allocation of resources.
Following the success of System Shock 2, Irrational opened a second studio in Australia and continued to work on anticipated sequels like SWAT 4 and Tribes: Vengeance. The studio endured some disappointing setbacks as well, with the hellacious PS2 game The Lost falling by the wayside.
In 2002, Irrational released Freedom Force, a game that combined Levine's and other team members' love for comic books with the open-ended character progression model that had worked so well in System Shock 2. The game wasn't as successful as Levine's earlier work, but it found a loyal cult following and Irrational self-published a sequel in 2005 with Freedom Force vs. the 3rd Reich.
It's hard to argue there is any game more definitive of Levine's career than BioShock. The 2007 shooter began as a successor to System Shock 2 that Levine hoped to structure around the idea of combat with a flexibly tiered array of enemy AI. The same basic structure of weapon upgrades and special magic abilities from System Shock 2 would return as Plasmids. This basic structure was combined with Irrational's most evocative game environment yet, an art-deco cross between Ayn Rand and The Shining, a book Levine claims to have read fifteen times in his youth.