To start things off, I should probably mention "The Illusion of Gaia" is the first video game I ever successfully beat as a child, so my review my be a little biased due to fond memories from playing the game and taking turns with my siblings. That said, I will do my best to keep my views subjective to give a quality review because the game deserves it. Over all, I rated the game at a 9 because while it's an amazing game (come on, who doesn't want to travel the ruins of ancient civilizations while defeating demons created by an evil comet), there are a couple of irritating factors about the game play.
   The first problem I noticed was in the first part of the game and happens occasionally throughout, but not as much. When you're sent to the dungeon, all you can do is wait for time to pass. When I first started playing, I had no idea what to do, so I kept thinking I chose the wrong decision, or my game was glitching. Then I would restart. That was very frustrating indeed. Another frustration was the lack of being able to travel to a place you have once been if it is not necessary for the story line. You start in the town of south cape, and eventually you are not allowed to return which makes the red jewel side quest impossible if you forgot to get all three in the town before you weren't allowed to return. This happens later throughout the game, but not as bad once you progress far enough. Although it only affects a side quest, from a completionist stand-point, it is very frustrating. The Red Jewel side quest is a fun part of the game, which gives throwbacks to a previous game in the series: Soul Blazer. That's one of my favorite parts of the game. 
    Although Soul Blazer and Illusion of Gaia are in the same series, they follow different story lines. However there are similarities, mostly involved with the Red Jewel side quest. Some other similarities include the monsters that you fight, and the concept of receiving an award for defeating all monsters in the area (among other minor similarities including graphics). As far as graphics are concerned, I found the sprites adorable. Owning the pamphlet that came with the game at home, I also got a chance to look at the actual art for the characters, and the sprites do a pretty good job portraying the characters they are meant to portray. Of course, the dialogue sound effects also help. For Kara, her speech is represented by a higher pitched bleep, while Lance is portrayed with a lower pitched sound. This also adds to how incredible the sound is for the game as far as I'm concerned.   I found the soundtrack for the game to be one of the most enchanting soundtracks I've experienced during game play. Although you can tell the sound is very computer generated, the musicality of the soundtrack seems to almost make you forget that it's not an orchestra, and you can appreciate the music for what it is. Yasuhiro Kawasaki did a fantastic job when writing for the series (something I consider heavily when I review a game, being an aspiring composer myself). Music from different parts of the world use different tonalities and musical modes, and I feel that the composer captured that well. For me, that's enough to make the game incredibly addicting   Part of it may be my nostalgia, and part of it the music, but there's something else. There's s omething that makes this game truly addicting for me. I think I've beat it a total of eight or nine times in my lifetime, and I'm still wanting to play it again. I will say that because the game is so storyline driven, it's hard to do a play through two times in a row. You already know the story, and it gets a little bland once repeated, but over time the game keeps drawing a person back in.   The story line keeps the classic adventure story line: Go on a quest to save a loved one, and save the world with the new power you suddenly receive, but there is so much more to it than that. The way I interpret it is almost an explanation of the idea of pangea. You are in a world, that will suddenly be changed by the comets light if you don't do anything to stop it, and the end result is shocking, yet familiar still. Included actual ruins that exist in the world gave the game an almost "real life" adventure feel that many fantasy games are lacking. Though, making it seem more real did seem to remove some depth from the game because that caused the story line to be more straight forward.   The majority of the depth this game provides is in the Red Jewel side quest which is very difficult to complete because the Red Jewels can be hiding anywhere. The quest is worth it, though for three reasons. It adds some difficulty to the game, it will assist in level your character up to a certain point, and if you've played Soul Blazer, you will appreciate the reference Illusion of Gaia makes to the game. Other than completing the Red Jewel side quest, the only other thing you can do in the game is progress the story line and fight the bosses. With practice, the game can be completed in a day or two after you've figured out the puzzles which are sometimes made a bit too easy for my tastes. That said, if they were too hard, it would make the game a pain and too difficult to truly enjoy the simple, yet engaging story.   As far as difficulty of the game overall goes, I'd say it's not hard, and it's not easy. You definitely have to be able to solve some form of puzzle, and have a decent memory to progress in the game, but a lot of the puzzles are spelled out for you if you pay close attention to the dialogue. For example, a person may note something strange or different about you (to avoid spoilers, I have omitted specifics), and that will be the answer to a puzzle further along in the game. The attack system is very basic and easy which is nice, but can sometimes get bland if you master learning how to attack and block quickly. Over all, I think that factors such as difficulty and depth were set aside to bring attention to the story line which I believe is the main focus of the game. If you're looking for a game that will prove enough of a challenge to keep you playing, but mainly focuses on well developed storyline concepts and characters, then this is the game for you!