

Blue Shift was originally a bonus campaign for the Dreamcast port of Half-Life, which is why it was so short and didn’t add any new mechanics. When that port was canceled Gearbox turned it into a full paid expansion despite it having a fraction the content of Opposing Force.
There’s a weird level of hatred for the HD pack. Almost every video I’ve seen on the expansions shits on it and tells you to disable it in favor of the classic look.