sentences:  Later id products continued to be ported by David Kirsch and Timothee Besset, a practice that continued until the studio's acquisition by ZeniMax Media in 2009.In 1991 DUX Software contracted Don Hopkins to port "SimCity" to Unix, which he later ported to Linux and eventually released as open source for the OLPC XO Laptop.Other early commercial Linux games included "Hopkins FBI", an adventure game released in 1998 by MP Entertainment, and "Inner Worlds" in 1996, which was released for and developed on Linux.