I somehow managed to download it from Angelfire.
Here's a MIRROR: http://a1win.loota.fi/files/half-life/gash_v2.zip

I ran past the three first sniper places a few times but got annoyed then. Maybe I'll try this sometime with my friends

The crates outside looked a bit too "blocky" since there were tons of them over one another. Otherwise at least the beginning looked nice...