Donkey Kong is an arcade game where you have to move the main character across a number of platforms while avoiding obstacles.
You are Mario, and your job is to get up the ladders and save the girl. You'll have to be quick to jump over the barrels that Donkey Kong throws at you as you go up the hill. If you miss, the game ends. It's hard to know when to wait and when to climb a ladder. Keep an eye out because barrels don't always fall down stairs. Donkey Kong will throw a metal barrel at you at the start, which will light a flame man on fire and make him slowly follow you from behind. When you get close to Donkey Kong, the barrels will come at you in waves, making the game harder.
Have fun and good luck!