You could say that is a refined version of CSO.
The big difference between Ultimate Counter Strike and Counter-Strike Online is that this mod includes many new features such as ranking, new shop menus, and much more. Counter-Strike Online uses Counter Strike 1.6 as its base, along with the AMX Mod X and Metahook plugins. Counter-Strike Online was originally developed by the South Korea developer Nexon Corporation under the supervision of Valve.
