Beth is a good shout but I didn't include it imo they do the same thing as DA but not as well. FO:NV is recognizable as NV etc. Plus attention to details and all the rest. WC/SC I am biased towards as they were my first games.
It's a bigger question than you think but I'll give it a go at answering it. The thing you have to bear in mind with ME series was that it's a game you can spend hundreds of hours in and not get bored. Personally I spent over 400 hours on 1, 328 on 2 (on steam so it checks
) and only 60 on 3, half of which was spent in multiplayer. Base of operation is a ship called the normandy and the biggest "city" is the Citadel, a massive space station housing billions of...things.
Throughout this series you play as Commander Shepard, general badass or paragon of humanity depending on how you want to play. You are obviously the centre of attention, before the game even starts you're a war hero and respected member of earths military. Then you touch an ancient device used by a former race called the Protheans which they used to store memories on. Everyone else that comes into contact with it is killed but Shep manages to survive and has a garbled version of the Prothean memories that are a warning against galaxy wide extermination -
dalek Reaper style (Sentient machines that warp your mind until you become their slaves). Along these hundreds of hours of gameplay Commander Shep as I said is the main person in events spanning the galaxy but there are always supporting members that are frequently featured and squadmates that are with you throughout this who are almost as important. (See Tali/Liara/Garrus love on any site that says a word about ME).
You make choices throughout the series which can have massive or minor consequences (Save a rookie from dying? He'll be back in ME3 to give you a modified weapon he's been working on. Save a planet, they create a statue of you and *Playername* becomes the most popular baby name for the next decade. Plus somebody makes a movie about you
). So after these eighty hours or so of a single playthrough of ME, the last *5* minutes manages to portugal up an entire series.
There are so many Reapers (bad guys) that the galaxy has to unite and stop them. So being Shep, you achieve this, even flawlessly, but still it matters not. Your scientists that you've been donating to create a superweapon capable of killing reapers (really frickin hard).
This is the part that gets infuriating. Nobody knows what it does or how to use it. Ok I say, whatever, we'll fire it and see what happens I guess. The final showdown between yourself and the antagonist arrives and it's a dialogue scence. Ok well that was pretty cool, if a bit weird. Then you get sent up a random lift in the middle of the Citadel onto it's roof and there sits a child made of sparkly glow dust. The weapon is now in front of you and has apparently slotted into a part of the citadel. Ok, so now they figured that out and transported it there from the opposite end of the galaxy....how exactly? Whatever, I'm sure they'll explain it later. Then the 'Star Child' talks to you about destiny and how Reapers are necessary to kill off all sentient life before they creat AI life that wipes out sentients. That's right, he sends robots to kill you all so that you don't make robots that are going to kill you all. At this point I am wtf'ing all over the place. It's messy.
Then the starchild gives you the power to choose one of 3 different coloured lights and somehow because you're Shepard if you throw yourself into them it powers the superweapon and defeats the reapers. The three different coloured lights are supposed to be choices but they don't do anything differently. It's such an indescribably bad ending to such an amazing series. The aftermath, nothing is explained. Nobody knows what happened to anybody, there is literally no closure on anything and then it ends with your ship crashing onto a plant and stranding your crewmates. More WTF'ing.