It was made by former professional level designers who applied their skills toward a pet project they clearly loved. Rock 24 probably gets my vote for the most underrated Half-Life 2 mod. Rock 24 - Henley Bailey and Richard Acherki It shows how preparing the same, old ingredients in a new way can yield interesting results.

Minerva Metastasis is a textbook lesson in minimalistic game design. Even better, he mostly avoids the load times that have plagued every official Half-Life release. It’s short - three to four hours, so I don’t want to give too much away - but Foster manages to use the familiar tools of Half-Life 2 to create something that approaches the quality of an actual Valve product. At first, you get the sense that she is pushing you through a rat maze, but the game opens up as the player’s changing relationship with Minerva becomes the focal point. You play as a captured Combine soldier pitted against his comrades by a mysterious woman named Minerva. The entire game is a linear adventure that takes place on a tiny island, but despite its linearity, it feels like it’s happening in a real, dynamic space. The guy who made it, Adam Foster, was actually hired by Valve. Minerva Metastasis is probably the most popular and highly praised Half-Life 2 mod.