I wouldn't mind if we don't see them coming back... a nice little appearance in a cutscene would be neat, but I don't really feel the need to see them coming back in gameplay.
à can see them work very well in 3D. On top of that, they were very well designed as a foe in gameplay, look and story-telling terms. In general, Greeters are awesome and deserve a comeback.
I can, for levels where the key is sneaking and subterfuge, it would be great, you know to have to dodge the greeters LoS and if you get caught, they raise alarms and try 'n zap you.
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Oh yeah, fair point. Maybe he was just tortured until he lost consciousness.