Which games similar to Mass Effect?

If you have the old version of Skyrim (Oldrim) on PC, I'd recommend looking into the total conversion mod Enderal. It's a lot more linear and character-focused than Skyrim, with a new story, land, and protagonist.  It's a completely new adventure.  It's also fully voice acted and available in both English and German. The writing reminded me a lot of Bioware, so if you enjoy Dragon Age and Mass Effect--you really should check it out!

Here's the trailer:

Kingdoms of amalur reckoning

I cannot think of a lot of RPG that are set in space, a lot of people associate RPG with fantasy over sci-fi and action games are in the space setting. I think that is why Star Wars 1313 had so much interest.

Hmm. You might want to give The Old Republic a try, even though I only played it at launch the leveling process feels pretty close to Mass Effect, at that point in time what let the game down was a lack of endgame I just don't know if that is still the case for the game. It is a F2P MMO so there are going to be restrictions. Another F2P MMO that isn't as good is Star Trek Online, but it really doesn't have the same feel since it is just a lot of dialogue and systems, no real choices for you to make.

Not at all, it requires SKSE.

The other folk pretty much covered it, not really anything else out there close to ME. Though I have 2 other suggestions, albeit different genres of game, but you could still apply a Mass Effect feel to them if you wished.

X-Com 2 is a pretty awesome sci-fi, mostly turn based combat with dice roll for your attacks, hits etc. (Just had a massive expansion pack released too!) Also has a little bit of straight forward base/economy management, and you can near fully customise your soldiers with lots of cool stuff. (Tattoos, face masks, cigars, glasses etc.) Even better you can get mods to expand that significantly, including voice packs, and yes there are Mass Effect skins/voice packs/music you can download since the game was made on the Unreal engine.

I'd still be hooked on that if I wasn't suggested to pick up Stellaris, which is a sort of space empire building game, a real-time version of Civilisation I guess, though time moves in days as opposed to months/years. Been playing the absolute crap out of it, you do need to get the additional content packs IMO, to really get the full value of it from the extra features/elements they bring in. Also a game that can be modded, and again you can get Mass Effect music, UI and Alliance ship skins. It's a slow-burn game, and can even seem boring at the start, but it really picks up once you get some tech research done. There is also a Star Trek total conversion mod, even in the current beta version it's been rock solid stable, and adds so much it's like having another game.

I like KOA but it is nothing like Mass Effect. There is virtually zero character development (outside of abilities) or choice and consequence, not to mention a lack of companions.

I know it's not space opera or even sci fi but the DA trilogy feels the closest to me because it's built around companion interaction and character development. That to me is what made the OT really stand out. There just aren't many games that focus on this combination as the top priority.

EA bosses: "Hey, we have a complete unique gaming niche with Space scifi shooter action RPG. Let's fuck it up."

ME is really the only space opera rpg I can think of (well there is KOTOR but that game is 14 years old). You would think there would be more but it is unique and then the stupid internet has to go and try to murder ME.

I would have thought someone would have updated that for the SE by now.

Yeah or the Deus Ex games tbh that's the only one I can think of that's remotely similar to ME although you don't command a squad in that.

Indeed that's the most frustrating thing about it.

There's some really old stuff available on PC. Can you handle DOS games?