Shadow of Mordor has created an emergent gameplay system that allows the game to explore a single theme in depth, the nature of revenge.
I just got the Brand ability, which allows me to take over the mind of an orc and have it fight for me. I can do this easily mid-combat, so I can very quickly turn a horde of enemies against itself, then stand back and watch the battle. I also got the Shadow Kill ability, which allows me to teleport to any orc and instantly kill it. Or I can use my flaming arrows or my “infinite executions.” These are all late-game abilities in Shadow of Mordor that make it easy to slaughter countless orcs. The horde that once frightened me, that I once ran from on a regular basis because it was too much to handle, is now my playground of death and decapitations, made even more fun by the fact that reinforcements just keep showing up, so my genocide never has to end.