Canalboy, October 29, 2019 - Reply Warp. Tough as a titanium coated pair of old boots. Massive and unforgiving mainframe game.
David Welbourn, January 16, 2010 - Reply I hope you mean games that are hard yet still fair and solvable, as opposed to games that are unfairly hard because you have to read the author's mind or require finicky wording in the commands.