This pack is a compilation of skins about their original design in the good ol' Half-Life.
Gman's eye is blue, briefcase is black + logo and skin tone change
Scientists' slacks are white
Guards' uniform has a purplish tint. No stripes. (Credits to J.Barnes)
HEV suit on their original colors
Vortigaunts are more brown like in HL
Barnacles are very reddish, white tongue.
Marines on urban splitter camo and has the HECU logo. (credits to sgtpieman >and lestat_cv22)
MP5 is gray.
Gargantua is brighter and has different hue slightly.
Shotgun is black, white tritium sights.
Alien grunts are brown, their armor has a purple tint like HL
Hivehand has magenta, purple and reddish color scheme
Controllers are more orange.
Crossbow's wood stock is darker.