Mass Effect games are always fun to talk about, never sure if I love or hate them more.
The 1st game in the series undoubtedly plays most like an RPG of the 3 games, though even then, it would stand as a rather odd RPG when compared to others.
For those that have played BioWare's best work: Star Wars Knights of the Old Republic, you'll notice some similar sub-stories, characters, and styles. I mention this only because the influence is strongest in the 1st game, when the series hasn't really defined itself completely.
Anyways, it stands as the black sheep of the trilogy for its odd mix of RPG and 3rd person shooter mechanics. It does, however, possess strengths the others lack. The Lovecraftian horror influence is pretty clear in some of the side quests that take you to remote planets -- the fear of the unknown, the ominous music all play into this.
The vehicular sections on the remote planets are a bit clunky, but they do a good job of establishing mystery -- you don't know quite what you're going to find. This works well in both reinforcing the trilogy's whole narrative and the general style the narrative embodies: the unknown, powerful threat, the dirty/dark sci-fi.
Of course, one has to forgive the incessantly repeated interiors and textures for the side quests, this game lacks polish. If one can get past it, one will find a series of stories that help add to and fill in Mass Effect's universe, even setting things up for the sequels well.
If one does everything, the game will take roughly 45-50 hours. If one moves through the narrative alone, you can complete it in 10-15 hours.
The main story narrative has the strongest KOTOR infuence. KOTOR was a campaign across a series of planets, not an entire galaxy. Mass Effect too, is composed of fairly long missions on a small handful of planets -- each a sort of individual story that connects to the larger narrative. Or there's the fact that in both KOTOR and ME1, the player follows the antagonist, or rather retraces their steps, to discover their motivations and goals, across different planets.
This is contrasted, then, with Mass Effect 2 and 3, where the meat of the games is composed of much more compact and exposition heavy missions with a lot of tight, polished shooting across many locations.
The shooting mechanics seem to, in principle, be based on what many call a Gears of War or GTAIV cover based system. Player pops in and out of cover. However, it's pretty clunky, the player doesn't stick too well to cover and cannot navigate it very well.
Add in the fact that weapons, armor, and upgrades are doled out in a traditional RPG manner, with damage stats being compared, unique drops, the skill point based system of character leveling. and a huge inventory to sort through, and one will begin to notice that things seem out of place.
It is not so much that these elements are bad in and of themselves, but more that they don't belong together. As if the developers were unsure of what kind of game they wanted Mass Effect to be.
After several replays, I've come to realize that they don't do a very good job of leading up to what is supposed to be the central twist of the narrative, the big reveal about the focus of the whole trilogy, the thing to make the games all connect. Avoiding spoilers, I mean the event with the 'virtual intelligence' on Virmire late in the game.
Anyone replaying will notice that the game will go so far as to basically tell, through other characters, the player directly what the narrative reveals later in a manner obviously meant to be climactic. It is again, odd, unpolished, and atypical of BioWare, much like the entirety of the game.
Besides feeling out of place and sometimes unpolished, the game has a lot of content, has mechanics that work even if feeling awkward, and manages to present an engaging narrative -- I still get rather excited when Joker commands the fleet upon Sovereign in one of the final scenes. Mass Effect's cinematic presentation is fantastic and never fails to make me feel invested in the story.
(If, again, one can forgive some of the cliches like checking the body of the villain to make sure he's dead only to discover him alive or thinking the hero is dead only to have him reemerge triumphantly. I think it is possible to view these little storytelling sins sympathetically, cute little mistakes of young Mass Effect)
I spent around 150 hours (100 on my Steam copy) on this game over several playthroughs. As I said at the beginning, I have a lot of issues with the series and it definitely isn't perfect. I can't deny though, that they do some things so well, and are so unique that they are games we can conclude are worth playing, worth discussing, worth evaluating.
Despite the game's flaws, odd qualities, and weird inability to define itself, I have to recommend it for all it does well, for starting a great trilogy and for leading into the best game of the series: Mass Effect 2.