Research and Development is a puzzle-centric mod for Half-Life 2: Episode Two featuring an unarmed player but plenty of violent mayhem.
This review may contain spoilers
A truly fantastic mod.
The puzzles are diverse and interesting.
Some parts are frustrating (Cart riding with grenade throwing enemies, and the start of Chapter 4), but the rest is a real blast... literally.
There's also some funny momments and a few references (e.g. A-Team).
The only reason it's not getting a 10, is that it took me 3 hours to complete, which is too short. Others might get more time out of it, so I imagine it deserving a higher score for those cases.
Overall, it's a must play, and i cannot wait to see a sequel to it!