Re: Mass Effect games as Sci-fi
A bit of both. Some aliens obviously work best as makeup/costuming (Asari, Quarians, Drell, Batarians), some may need slightly too extensive prosthetics (Salarians, Taurians), and others would need to either be an extensive puppet or completely CGI (Krogans).
'Spock is always right, even when he's wrong. It's the tone of voice, the supernatural reasonability; this is not a man like us; this is a god.'
- Philip K. Dick