to people selling their WADs for money, some WAD sets and shovelware bundles were nonetheless obtainable for a price at certain outlets. During this time, id Software was working on their next game, Quake, using new technology, but started projects picking up the most talented WAD makers from the Doom community to create official expansions and to compete with the unauthorized collection CDs. The team produced the 21 Master Levels, which, on December 26, 1995, were released on a CD along with Maximum Doom, a collection of 1,830 WADs that had been downloaded from the Internet. In 1996, Final Doom, a package of two 32-level megawads created by TeamTNT, was released as an official id Software product. Various first-person shooter games released at the time use the Doom engine under a commercial license from id Software, as such essentially being custom WADs packaged with the Doom engine, such as Hacx: Twitch 'n Kill (1997). In addition to the many people who contributed to commercially released WADs, various authors became involved with the development of other games: Kenneth Scott, who contributed artwork to Hacx: Twitch 'n Kill, later became the art director at id Software and 343 Industries on the post-Bungie Halo games. Tim Willits, who contributed two levels to Master Levels for Doom II, later became the lead designer at id Software. Dario Casali, author of a quarter of Final Doom, was hired by Valve to work on Half-Life. Sverre Kvernmo, designer of five levels in Master Levels for Doom II and member of TeamTNT, was hired by Ion Storm for Daikatana. Iikka Keränen, author of several Doom WADs and later Quake mods, was hired by Ion Storm to create levels for Anachronox and Daikatana, and by Looking Glass Studios to create levels for Thief II: The Metal Age. Keränen was later hired by Valve. John Anderson (level designer), also known as "Dr. Sleep", author of five levels in Master Levels for Doom II and E4M7 in The Ultimate Doom, later worked on Blood, Unreal, and Daikatana. Matthias Worch (level designer) joined Ritual Entertainment to work on SiN. He later contributed to the Unreal series. Source port era Around 1997, interest in Doom WADs began to decline, as attention was drawn to newer games with more advanced technology and more customizable design, including id Software's own Quake and Quake II. On December 23, 1997, id Software released the source code