Well if you want to play with bots you can always download Bobot final version. Just follow the README.txt in the file and download it. Click start a new server, modify your options as you want and make a localhost game. Now just hit ESC > Options > Bobot and add bots and edit them as hard as you want.
-ily
EDIT: You can actually even edit fire rates and weapon damages in the program and make your own skins. It also has a really long list of guns that you can use so its fun to even try it out.