⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀ ⢰⠐⠢⡀⠀
⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀ ⠀⠀⠀ ⣠⠤⠤⢄⡠⢓⣄⠈⢆
⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀ ⢀⣠⣊⢨⠀⢐⣁⠔⡏ ⠉⠉
⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀ ⢀⠔⡿⡀⡨⢊⡣⢄⣀⣀⠇⠀⠀⠀
⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀ ⣠⢔⣁⡞⡙⢷⡬⣉⣘⠖⠊⠁⠀⠀⠀⠀
⢠⣿⣿⢢⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⡠⣚⡑⡥⠜⠈⠒⢶⡵⠋⠁⠀⠀⠀⠀⠀⠀⠀
⠀⠹⣿⣿⣀⠀⠀⠀⠀⠀⠀⠀⢰⣿⣿⣷⣆⠀⠀⡠⡊⢆⢣⣈⡎⢥⡶⠚⠁⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀
⠀⠀⠿⣿⣿⣄⠀⠀⠀⠀⠀⠀⢹⣫⣿⣽⠏⠀⡎⠀⠑⣏⣱⠶⠊⠁⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀
⠀⠀⠀⠹⣿⣿⣿⣿⣶⣖⢲⢲⢾⣿⣿⣧⣄⣔⠵⠰⠞⠋⠁⠀⠀⢠⣤⣿⣿⡆⠀⠀⠀⠀⠀⠀⠀⠀⠀
⠀⠀⠀⠀⠉⠛⠿⢿⣿⠈⢦⠇⡹⡚⣻⠷⣻⣳⢷⣶⣶⣶⣦⣶⣾⣿⣿⣿⠉⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀
⠀⠀⠀⠀⠀⠀⠀⠀⠘⢦⠔⣋⣷⣷⣿⣞⠋⠀⣼⣿⣿⠿⠿⠟⠋⠁⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀
⠀⠀⠀⠀⠀⠀⠀⠀⠀⡼⣿⣿⣿⣿⣿⣮⡶⠊⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀
⠀⠀⠀⠀⠀⠀⠀⢀⠴⣷⣶⣿⣿⣿⣉⡻⠁⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀
⠀⠀⠀⠀⠀⠀⢀⠎⠀⠘⣿⣿⣿⣿⠿⣧⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀

Nice little campaign of security guard Barney Calhoun in Half-Life world. The puzzles and story were on point.

Time to beat: ~2.8 hours
Half-Life: Blue Shift puts the player in the bullet-proof vest of Barney Calhoun during the Black Mesa Incident! There's no fancy new content or multiplayer mode (NPCs & weapons are all what you'd expect from HL1), but despite taking place in the same general area, the levels here are all completely new.

If you really enjoyed Half-Life and want to squeeze a little more gameplay out of it, then I'd absolutely recommend this. I would not play it before HL1 though!