When an encounter card with the surge keyword is revealed during the staging step of the quest phase or in setup, reveal 1 additional card from the encounter deck. Resolve the surge keyword immediately after resolving any when revealed effects on the card.
When setting up Desert Crossing, the players are instructed to "place the heat tracker next to the quest deck and set the temperature to 10." To do this, take an unused threat tracker and place it next to the quest deck. For the rest of the game, that threat tracker is the heat tracker and the value it displays is the "temperature." If the temperature reaches 60, the players lose the game.
To play normal mode, just follow the setup instructions on the quest card.
When you play normal mode (or easy mode of course) and if you're new to the game, you can also play the "Basic Game" defined in the core set rules:
Newer players or players who want a more basic experience can play and enjoy the game by not dealing shadow cards during the combat phase. This eliminates an element of surprise that could make the game too challenging for a beginner. Once players are comfortable with this experience, they can then add the shadow effects to make combat less predictable and more exciting.