Example: a dystopian city full of raiders or whatever enemy you choose.
Main Character (You) and Companions
Example: A convict and an abandoned dog.
Example: A rebel wants a disabled person to move but the disabled person is meeting a person and cant contact the person. If you choose to move the person then he will not help you later on but if you choose to leave him alone then the rebel will fight you.
Firstly, set the scene for your game or puzzle.
Travelling and Items
Example: Man holes can take you to sewers or other areas that are inaccessible.
Next you will need to add your character. If he has any companions then you can add them too.
Mini Map and Mission Markers
Sometimes in games you are forced to make decisions. When you make decisions, they can effect the game-play.
Left Example: The main character saves his son from his sons kidnappers.
Right Example: You save your son from his kidnappers but you get shot/killed in the process.
In some games there are locations where you can travel/fast travel to other locations. There are also drops and containers with items inside.
Example: Suitcases can hold valuable items such as weapons, crafting items and consumable items.
In some games there are mini maps which can help you navigate through your world. It can even show your current objective.
In games which rely on your choice may also have your choice affect the ending. Games that are like this are normally full world exploration games with a main quest and side quests through out your world. An example of a game is Fallout 4 and the different endings can be changed if you join different factions.