Need to start some were in modding right? Why not try the Half-Life modding Kit. This Kit is designed to have all the tools you need to start your own Half-Life mod, simple mods can be made or advance ones like Base Defense with this small set of tools. If you want to start modding Half-Life you should try this.
I was checking the archive file for the changelog when I noticed it was missing, This is important because the change log has the impulse commands in it so here is the archive with the changelog, the installer already has a changelog so don't worry if you used that