Is there any way that a game made with the free version of Unity can be integrated on Steam. I’m not talking about achievements and so on. I’m just asking a about a basic integration where you can only play the game on Steam.
You can submit a game to Greenlight for it to possibly be on Steam eventually, if that’s what you’re asking.
Only if Valve waived the requirement of integrating their SDK by now.
Otherwise you can’t do it as binding external unmanaged libaries legally requires Unity Pro