The Adventure is set in the mythical land of Xanadu. Your task is to explore the terrain, find all the treasure and get the highest score you can. To help you on your exploration, you start with 125 shillings which you can use to buy provisions in the Adventure shop.
When two Adventurers play, they take it in turns. Each player has a fixed number of turns and then the other player takes over. You can either explore as rivals or as allies. As rivals, it's probably best if you don't watch the other person's progress. The person whose round has ended should go away to wait for his next round. As allies, you still take it in turns, but anywhere you go your ally comes with you.
In fights with monsters, your combined weapon count is pitted against the monster. While you're allied, it's best if you both watch the screen all the time.