"Hey! The door opens. Peter, go first and tell me what is going on inside." "Yes Sir!" No sooner Peter had entered the room, the door suddenly closes behind him. Peter is now trapped inside the room and all his companions are waiting outside. To find a way out, Peter must collect the bulletproof key to fight the approaching fireballs. "Oh find one!" "Can you hear me, chief?" "Yes, we hear you" "Hey! There is another room. I'm going inside." "Yes, go Peter. Good luck."

Expedition was of course inspired by arcade hit Berzerk, but adapted to the limited features of the SD-2xx systems. There is no real maze, only square chambers with monsters inside.

In each chamber you must collect the magic key in order to be able to shoot. Then destroy the fireballs while avoiding the other obstacles. You must destroy 4 fireballs for the exit to appear.

You will die if:
- touch obstacles or fireballs
- time is out
- you are touched by bullet from the fireballs

There are four game options which differ by the total number of lives available (6 or 8) and time limit for each chamber (60 or 70 seconds).

There are 9 different chambers. In the three first ones, the fireballs will not attacks, then from n° 4 to 6, one fireball will shoot you, finally in the 3 last chambers both fireballs can shoot you simultaneously.