In the Mass Effect series players talk on the role of Commander Shepard, a human fighting to defeat the Reapers- a species of enormous sentient machines which are bent on eradicating all intelligent life from the galaxy. The cool thing about Mass Effect is that as Commander Shepard you are forced to make moral decisions constantly. These decisions often have far-reaching effects and can alter game events drastically.
The two morality paths are Renegade and Paragon.
Compassionate and heroic actions. Lawful good doesn't mean lawful nice- Shepard is a badass who is absolutely dedicated to his mission.
Apathetic and ruthless actions. The stakes are just too high- failure is not an option, sacrifices have to be made to ensure the success of the mission.
From the Mass Effect Wiki:
"Unlike many contemporary roleplaying games (video games) that represent morality as a single sliding scale of good and evil, Mass Effect keeps track of the Paragon and Renegade points on separate scales. A good action will not make up for an evil one; therefore, being nice occasionally will not stop people from fearing a killer or remove the reputation of an unsympathetic heel, but nor will the occasional brutal action significantly damage the reputation of an otherwise upstanding soldier. This also means there is no gameplay-driven motivation for avoiding a particular type of action."
This leads to players choosing the option that feels right for "their" Commander Shepard. I normally play a character who is very Paragon oriented, but I didn't hesitate for a second when a quick-time event popped up on screen- giving me the option to viciously attack the mercenary captain I was having a conversation with. A young girl's life was at stake and I felt like my Shepard would be ruthless to save her.
Although this may seem like a pretty narrow set of choices it is very much in character with the game background and makes a lot of sense within that context. I think this is a pretty good demonstration that the important thing about a alignment/morality system is that it fits the feel and flavor of the game being played and not how it looks "on paper".