@mewfeuille The two most important parts of the game are the very southern tips on both sides.
Bottom right by the shrine area has better spawns for the Gold Golems (which you grind up ~8000 gold on to get the Magic Armor), whereas the bottom left area by the most southern bridge has the Metal Slime spawns.
The charm of the game lies in its simplicity; you're never going to find a more pure JRPG than this.
but boy, it's short