Complex sentence: Valve has placed a strong emphasis on the independent developer as well as user developed content, as is demonstrated with Valves Steam workshop platform, a feature of Steam, Valves gaming ecosystem featuring hundreds of millions of active signed up users.
Split into simpler sentences: Valve has placed a strong emphasis on the independent developer as well as user developed content. It can be seen with Valves Steam workshop platform, a feature of Steam, Valves gaming ecosystem featuring hundreds of millions of active signed up users.