Tales of Phantasia is an absolutely great, but underrated, RPG for the GBA. By the way, you have to use a GBA SP.
Like every RPG, it has one main map with cities, ports, caves, etc. scattered everywhere. You start as a guy named Cress Albane with this crazy pendant thing that's the key to unlocking some evil god named Dhaos from some tomb in the catacombs. What is REALLY annoying about ToP is that encounters are WAAAY TOO COMMON. Of course, there are items called the holy bottle, which decreases the monster encounter rate, but they last for only a little while. And when you're in a dungeon without any holy bottles, it's gonna be hell. Just try walking 5 steps without a monster jumping on your back.
Main Map: Weee you can walk around and stuff! There are ships you can use to cross the oceans to designated places. There's a price, though. Later in the game you get planes, so you can traverse the whole world without random encounters! Go across the seas, the mountains, to islands.....
Battle: Ah.....I love the battle system so very much :D It's not the boring old fashioned turn based thing. You can think of it like a fighting game style. You're Cress and you have a sword on a 2-D platform thing type of battle field. The left and right buttons make you move left and right -.- A is to slash and here's the good part. The B button is for using special skills called Deadly Skills and Secret Skills. The B button can also be with the D pad buttons to perform other skills (B->,