Destroy plastic monsters in small dungeon...
with only pistol...
go around a small dungeon, beat the plastic monsters and win gold. The collected gold is converted to won and used to raise its HP. You can even buy a house, buy furniture, collect electronics, and even make more than 10,000 by HP! Of course, you can upgrade a single gun! With this increased HP and gun power, you can easily and quickly get more gold and move towards a better
However, aiming is difficult. They will move strangely...
and.. with only pistol...
Way to go!