While there was one puzzle at the end of the game that's solution was kind of annoying, the rest of Blue Shift is one of the most consistently good parts of any of the gold source HL games. This might have been recency bias since this was the last gold source HL game I played, but I liked pretty much every aspect touched in Blue Shift more than I did in opposing force. The new additions and features in the game that made it stand out from the original, while having far fewer than OF, utilized it's new features a lot more than OF as the more grounded nature of Calhoun made me really think I was an actual security guard escaping the madness of the black mesa incident, more than Shepard in OF which just seemed like a less powerful Gordan Freeman. I also liked the atmosphere a lot more, as playing through the earlier stages and seeing more of Black Mesa, and then having to run around for the first few minutes after the incident played a lot into the horror aspects of the game which I really appreciated. Overall while both OF and BS are good games to play after beating HL1, I would strongly recommend BS over OF, as I simply just liked it more as an experience.