Freeman's Mind uses Half-Life: Source, which is Half-Life 1 ported (no new models or textures) to the Source engine (which was the one used for Half-Life 2). Ha

Freeman's Mind uses Half-Life: Source, which is Half-Life 1 ported (no new models or textures) to the Source engine (which was the one used for Half-Life 2). Half-Life: Source was released at the same time as (or right after?) Half-Life 2 in 2004. Black Mesa is a recreation of Half-Life 1 in the modern Source engine completely from scratch. I've followed its development for over a decade and have been consistently impressed by how good it is. They just released the last couple chapters too, so now's a great time to try it out.