This Skyrim mod recreates the best part of Shadow of Mordor: the nemesis system

pcgamer.com:

As a heroic adventurer, it's easy to cleave your way through mobs of enemies, leaving a wake of anonymous corpses behind you. Who were they? What were their names? There's little reason to know or care. And even if one of them is tough enough to defeat you, you can just reload your last save and try again until you kill them, the ultimate cheat code.

But 2014's Shadow of Mordor added a compelling wrinkle with its nemesis system. When an uruk or orc defeated you, it would receive a promotion and rise within Sauron's ranks. It'd grow in power and get a catchy nickname, becoming far less anonymous. Your nemesis suddenly felt like an actual character, turning combat with them into bitter grudge matches. Random orcs even became famous in some circles.

Now you can experience those grudge matches in Skyrim too. The Shadow of Skyrim — Nemesis and Alternate Death System(opens in new tab) mod makes any enemy who defeats you into your nemesis, from dragons to trolls to bandits to, yes, even mudcrabs.

The biggest change is that now when you fall in battle you don't actually die, you're just knocked out. Instead of reloading your last save, you'll wake up somewhere else on the map. Some of your gear may be gone—in fact, your nemesis might actually be using your weapons and armor if it's superior to their gear. You may also have a debuff: for example, if your nemesis defeated you with a power attack, you might gain the «off-balance» attribute meaning you're more susceptible to being knocked down in combat. Your nemesis, meanwhile, has grown stronger and may have improved stats and a new buff of their own, making them even harder to defeat.

And of course you have a new quest in your log: revenge. Find your nemesis and destroy them.