Random elements in games include things like:

• where players spawn (start) in a landscape;
• what attributes they have (like level of player_strength or wisdom);
• where treasures to collect are;
• how strong or cunning enemies are;
• what level you go to next, and the design of levels;
• the chances of events happening.

Randomness makes a big difference to the realism of games, and how many times people want to play them.