Doom, the Roguelike Trivia (Windows)
Business modelAlthough it is listed here as being freeware, DoomRL actually is Donationware -- as all of Kornel Kisielewicz's games so far.
Legal threatOn December 2, 2016, ZeniMax Media, Inc., the owner of the Doom trademark, sent a formal takedown notice to Doom the Roguelike's developer, Kornel Kisielewicz, stating that the website's use of the Doom name infringes upon their intellectual property. Since Doom the Roguelike had been around for nearly fifteen years without incident, it has been suggested that ZeniMax had been prompted to do so after Kornel started a Kickstarter campaign for his new game, Jupiter Hell, which had been advertised as being "by the creator of Doom, the Roguelike" - which might be interpreted as exploiting a trademarked name for monetary gain.
In the end, Kornel Kisielewicz changed the game's official name to simply DRL, and all references on the official website to Doom, the Roguelike were changed to D**m, the Roguelike. The game's source code was also made available on GitHub, which was a move Kornel originally planned to do after the Kickstarter campaign ended.