Peace is usually not possible until a Civ has accumulated War losses. The Civ V SDK will begin downloading and installing within Steam.You should see “Sid Meier’s Civilization V SDK” as an available tool.
The Modding SDK is available as a free download on Steam: It’s actually the 24th most played game on Steam at the time of writing, and the highest strategy game on that list.
Now, Civilization VI stands far above Civ V in Steam’s player count. In-game, you can now press ~ (the key above TAB) to access the console and change settings. However, Firaxis did include a debug mode for developers that can be exploited to reveal the entire map and gve your Civilization infinite Happiness. You see, no cheat codes or command console of that type exists for the game.