Keep in mind that this is a fairly short and non-linear game. More than anything else, it reminds me of the first Dragon Warrior, as most of your time will be spent leveling up and buying new equipment. For this reason, this walkthrough will be short and to the point. Just remember to keep your levels up and check out the rest of the shrine if you need more detailed information on anything.
You start out the game in the town of Tedo. Head to the north end of town and in the far north house, talk to Old Rob. He'll give you a Telepipe and you can set out. Level up and upgrade your equipment and magic until you feel comfortable fighting the enemies across the bridge south of Tedo. When you feel comfortable, head into the cave northwest of Tedo. You might want to buy some Torches, because the Light you have increases power as your level goes up, and it's pretty weak at the beginning of the game. Anyway, work your way to the treasure chest, get the Scroll of Truth and talk to Old Rob again.
Sometime in the game, you're going to have to visit the Gypsy Encampment near the Desert south of Tedo. Now is a good time. Make sure you have 120 Mesetas saved up and go there. Enter the fortune teller's hut in the north. Ask for the Tarot Card reading and you'll receive the Kura Bracelet, which will be invaluable later on.
Across the bridge south of Tedo is the town of Mektor. North of Mektor is the town of Tinyville. Buy new equipment and magic if needed, and level up a bit. Enter the cave near Tinyville. This is actually the same cave you were in earlier. Take a few steps to the left and you'll fight Lao-Tse. Defeat him and you'll get the World Map, which isn't necessary, but is kinda useful. You can explore the rest of the cave if you want, but there's nothing important.
South of Mektor is the port town of Karkato. Along with new equipment and magic, you'll want to buy a "Ouzo" from the item store. Do so and head to the ruins east of town. Try to enter, and the guard won't let you. After you're kicked out, use the Ouzo. You'll be inside. There are no enemies here, and only one treasure chest. Get it and you'll receive the ATV.
Head to the desert (where the Gypsy Encampment is). With the ATV, you'll be able to cross. South of the desert, you'll find a cave. There's nothing mandatory about this cave, but there are some useful treasures, a Trimate, a Perseus Shield, a Typhoon Bomb, and a Patriot Ring. Furthermore, the enemies are the same ones you encountered near Karkato. Explore the cave if you want, if not, visit the town Porum, to the east.
After doing your thing at the town (be sure to buy a Telepipe!), head south into the forest. As soon as you enter the forest, try to exit and you'll be transported to a small house in the middle of the forest head south and work your way to the west. You should encounter a guy named Dirk. Agree to help him. Go back to the house and you'll get the Sluice Key. Now use the Telepipe I told you to bring and you'll be transported out of the Forest.
Follow the river northeast of Porum and you'll reach the sluice gate, but it's locked. Use the Sluice Key. Then spin the handle 3 times to the right and 2 times to the left. Then you should be able to drain the river.
North of Porum is Tarrytown. Further north of Tarrytown are four caves. Each of them holds something important. Get ready to do some exploring. The cave on the far left houses the Laconian Shield, the next cave to the right has the Laconian Sword, and the next cave has the Laconian Armor. These are the three best pieces of equipment in the game. If you have trouble finding them, visit the Maps Section.
That only leaves the far right cave to explore. When you first enter, you will be encountered by a RobotCop. Destroy him and move on. Work your way to the west, and eventually you'll meet Daedalus. Defeat him and he'll join your party as Lars, and Dirk will leave your party.
Now go to the area near the forest, but instead of entering, work your way around the outside corner to the east. You should find a cave. Make your way through this cave and you'll find a cryogenic chamber. Lars will open it and inside will be Alis (apparently the same one from Phantasy Star, but she looks much different). Alis will join your party, and Lars will turn into a pink car (which doubles as a boat).
Make your way to the water, which you'll now be able to navigate. Head to the far southwest corner of the world (south of Karkato). You'll find an island with a castle. Enter the castle. There is plenty of good treasure here, if you want assistance in finding it, go to the Maps Section. Anyway, make your way to the fourth floor and you'll encounter Cablon. The first thing you should do in this fight is use the Kura Bracelet. If you don't, you won't be able to win. Then just beat him like you would any other enemy.
As much as I'd like to continue, the game will end there. Have fun!