Half Life 1 was a fantastic first person shooting game released somewhere around 1999. This Blue Shift is the second rather dull expansion pack for Half Life 1. To be blunt, the first expansion Opposing Force is better, because it offers more guns, new gameplay mechanics and a lot of new monsters. Blue Shift however offers nothing new except new levels that will take you under 4 hours to complete the first time around.
Blue Shift takes you through Black Mesa and Xen once again when everything goes wrong and aliens invade. You start the expansion riding the tram to work (just like Half Life 1) after taking an optional training course that is literally the same training course from Half Life 1.
The gameplay is more challenging than the original game in both good and bad ways. The good way is the game shows off its artificial intelligence by pitting you... Barney Calhoun, a blue shift security guard at Black Mesa, against hundreds of marines sent into the Black Mesa facility. Usually you fight 10 marines at a time in wide open areas. The enemies will scatter when you throw grenades, run away from you, try to flank you and fan out so you're not shooting enemies like dominoes.
The negative ways that the expansion is challenging comes from several dark areas with dozens of head crabs jumping at you around every turn. It feels cheap compared to Half Life 1 and Opposing Force.
There are a few shining lights for this expansion and that is rescuing scientists, although it's not much of a rescue, because any of them can die and it doesn't matter. The expansion also dabbles in having an important character Dr. Rosenburg that you will rescue and he will guide you to the end of the expansion. Guide you as in briefly tell you what to do through believable voice acting.
In all this is a lackluster expansion compared to the previous one and feels more like a level pack... without levels, just one continuous game. Chances are you can get this expansion with one of the deluxe Half Life 1 games, so save some money and get Blue Shift there instead.