Make a simple course
Use soft ground and make a shallow hole that is slightly wider than the playing marbles. Mark a starting line several paces away.
Shoot from each resting place
Players take turns shooting toward the hole. After every shot, leave the marble where it stops. On the next turn, shoot from that position.
Keep the hole shallow enough that marbles can be removed without damaging them.
Choose the winning rule
The simplest version ends when the first player sinks a marble. A longer version uses several holes in an agreed order and finishes at the starting line.