sentences:  Popular early titles included "NetHack, Netrek, XBill, XEvil, xbattle, Xconq" and "XPilot".As the operating system itself grew and expanded, the amount of free and open-source games also increased in scale and complexity.The beginning of Linux as a gaming platform for commercial video games is widely credited to have begun in 1994 when Dave D. Taylor ported the game "Doom" to Linux, as well as many other systems, during his spare time.