What do you get if you mix Batman, Assassin's Creed and Lord of the Rings? You get ME:SoM. It is incredibly reductive to call it only a by-product of these three things, but since one of the first thing you do is eagle-dive down a tower and then activate your bat/ghost vision to see the bad guys and then you are fighting the uruks from the mind of J.R.R. Tolkien, it's hard not to compare ME:SoM to the sum of its parts. That being said, there are a few very interesting systems in there, notably the nemesis system.
Basically, the nemesis system populates the world with named chieftains with their own agendas, strength and weaknesses and power struggles. If you squeeze weaker orcs, they might give you intel on a specific chieftain - such as being weak against sneak attacks but immune to ranged shots - or you can find it in the environment. Then you go fight the bosses with your knowledge and you theoretically kill them with a mixture of batman combat - good old attack/parry/dodge - and some ranged shenanigans and some ghost powers. In practice, anytime I went to attack a chieftain, I got attacked by three of them at the same time and couldn't manage to kill them all, as I was at the beginning of the game, and the game didn't tell me to run away, so I assumed I could take them. When you die, enemies that killed you grow stronger, power struggles resolve and the world moves on a bit. These kind of deaths were my fault because you always can enter ghost mode to see where bosses are and I should have known that my attack was a foolish one.
That being said, I find the PC controls quite convoluted. Shift to sneak and do finishers, F to execute, E to ghost stun or to drain, spacebar to jump, left click to attack, right click to parry or to go into ranged mode, ctrl to grab enemies. Maybe it's better with a controller, but I didn't have the best of time with my keyboard and mouse. When you are almost dead, you can attempt a last-ditch effort to keep fighting by moving the mouse cursor into a circle on the screen and then pressing a key, I failed at this most of the time, and sometimes even if you succeed, getting hit again will kill you with no chance to come back. It's not that obvious to dodge ranged attacks and getting surrounded by a dozen of orks is a good way to die no matter what your dodging skills are - especially since you need the kill animation to finish before you can instantly dispatch your foes.
For killing enemies, you get experience, which is used to unlock new abilities - which I feel aren't covering as wide of a range as they could since I picked them up mostly because I could and not because I felt like using them. Throwing daggers using yet another key on the keyboard? No thanks. And you need to defeat enough chieftains before you unlock the next tier of abilities. You also find artifacts and runes on walls which gives you a bit of lore but also some money you can use to buy passive upgrades to your stats such as having more health or more arrows. Finally there are runes you get for defeating bosses, but while their bonuses can be nice, they are too specific for me. 7% chance to regain life when you kill an orc from a stealth head shot for instance, won't happen often. I wish they had more general bonuses like 7% health recovery whenever you kill something.
Besides that, there is plenty to do in ME:SoM, you find towers in each region of the map, which allows you to see quests and challenges you can do, you can also pick herbs and hunt animals for some bonus gold. The nemesis system will keep your interest for a while with the foes you will kill - or that will kill you - before you try again with a better strategy. If only I was better at that style of combat - or if I was better at knowing when to run away - maybe I would've made it further.