Game developer Mike Bithell has talked about the hows and the whys of stealing from other games before, and he's discussed why the menus of Destiny are so effective in that game. He's since turned his Sauron-like gaze to Shadow of Mordor, describing why other games should steal the Nemesis System.
"I bloody loved this game. What it stole, it improved upon, be it [Assassin's Creed]'s openworld design rhythms, or Batman’s combat system," Bithell wrote. "Crucially, they did a brilliant job of bringing freshness to the game via their Nemesis system and adjoining mission structure."
He describes game design as a series of magic tricks, things put in place to give the player the illusion that something amazing is happening to them as they play. He breaks down how the Nemesis system works, and shows that a small number of rather simple systems keeps the whole gimmick moving.
His entire post is worth reading, but his breakdown of how a relatively small number of assets is used to make an unlimited amount of enemies with personalities shows just how clever the system is in action.
"Obviously a random name generator is in effect, which is pretty straightforward to do. What’s clever is the way in which the name generator, art assets from which new Orcs are composed, and audio files for their voice and their allies’ voices are hooked up together to imply way more personality, and emergence, than is actually present," he stated.
The brute, the fatty, the camp, the idiot, and the fiendish — there are probably more, but I noticed about 5 ‘types’ of Orc. I suspect there might be a matrix rather than a list, but either way, those names and traits aren’t random. The game makes, say, a fat orc, then gives it a name (at random) followed by a qualifier from the fat list ‘the chubby’, then ensures it uses voice files from the fat [voice-over] pack. It’s amazing how much this makes the character feel cohesive.
He points out that this is repeatable in even small-scale games without breaking the bank, and the trick of creating of a world that seems much bigger than it really is can be a powerful tool. You feel like these real creatures are growing and learning and hunting you, while it's really just a few systems working behind the scenes. The game has personality, and that's a trick that's been used by other, equally successful games.
"This is the same trick Valve pulled with the AI director in Left 4 Dead ... by calling it a ‘director’ rather than ‘procedural randomised enemy spawner’ they made me angry at the dickhead director, rather than their code," he explained.
"I also imagined a far deeper system than existed. ‘Ahah! The director is going for an emotional reaction here.' The true system was brilliant and clever, but no code has yet been written than can match the genius I attributed to that code because Valve drew a smiley face on it."
These efforts to humanize your enemies, and then use those enemies to more or less troll the player in a way we enjoy, is brilliant. A few simple systems work together to create something that feels larger than life and complex, and it helps to make Shadow of Mordor one of the most interesting games of the season.