In what could be called one of the best single-player mods in the advent of Black Mesa, comes Research & Development. An hour long puzzle mod that has the player traversing an immense Combine-infested research facility without a weapon. Sound boring? -Not in the least bit. I had the opportunity to help playtest this mod myself, and the amount of polish and new gameplay conceived here is astounding. This mod will keep you on your toes the entire length and will reward you with new and exciting ways to navigate your surroundings. Truly a mod that will go down alongside the ranks of Minerva. Yes, it's that good.
Here are some links to help get you started:
Mod DB Profile
Interlopers Thread
File Front DL
And as always, you can follow up with any comments in the thread started up
here.