Adrenaline Gamer is a very flexible modification of Half-Life created by BulliT, allowing players to configure the server their way, with several gamemodes. It has been considered by the community to be the Promod for Half-Life 1.
Despite the latest version being 6.6, the community has released an updated client called [**OpenAG**](https://openag.pro/) that brings lots of fixes and also improving the experience.