GPhys

The experience Gorilla Tag was meant to be. GPhys is a sandbox, campaign, utility, and one hell of a cool Gorilla Tag mod that adds Half-Life 1-Alyx stuff, Black Mesa stuff, Portal stuff, as well as some other VALVe stuff into Gorilla Tag!

It is developed by Lambda Reclaimation, a sub-team of QuantumLeap Studios that specifically works on Half-Life styled projects.