Xenogears has the best story I ever experienced and that's enough to make it perfect.
Problem with Xenogears is that after Final Fantasy 7 everyone wanted another cinematic firework and Xenogears wasn't such kind of game. If FF7 is a blockbuster movie than Xenogears is a philosophical book. No wonder than sex-and-violence-oriented retarded specie like gamers, didn't buy a game that require thinking and reading, instead of just watching big amount of cut-scenes and pressing the X button for Massive Damage. Additionally to that Square hurt this project during development (part of money that was firstly supposed to be spend on Xenogears went for FF8 development) so game is a bit broken (I will explain that later). So after all that Xenogears franchise was buried before it was even fully developed.
If you are smart enough you might connect that game with Xenosaga series. And guess what? You're right. Xenosaga is developed by mostly the same team, known now us Monolith Software. However it's not a direct sequel/prequel because of rights hold by Square on Xenogears title. What is most sad in Xenogears is that it's fifth episode of story. Most of story was presented in special art-book - "Xenogears Perfect Works", which sums up 6 episodes of Xenogears, presenting human history on planet Gaia (on which game take places) and few thousands years before that. Xenosaga however take place even earlier and is a bit not fitting in some of the elements, at least for me but maybe later games would make it fit perfectly. Unfortunately we will never learn that because due to lame sell and Namco idiotic decisions Xenosaga died just as it older sibling. END OF THE SAD STORY.
OK, so now after I throw all my grudge against evil video game companies that destroy everything what is beautiful and noble in this business, I can focus on the game itself. As I said Xenogears can be compared to philosophical book. That's because the main power of it is story presented in it. Game handle us fate of painter Fei Fong Wong, who lives in a village named Lahan. He suffers from amnesia, and don't know too much about his previous life before he was brought to Lahan half-dead few years ago. But night when war enters this peaceful corner of earth everything start to change. Huge gears land at Lahan and start to fight. To save villagers Fei enters one of the abandoned gears and start to fight however he goes rampage and destroy not only enemies but most of the village itself. Cast away but survivors he start to travel to search for his past and meaning of life.
That's just a first two hours of gaming and I know it doesn't sound too amazing, However game is something like 60 hours long and believe me that with every hour it gets better and better. Xenogears story covers political, social and religious issues often in very deep and controversial for a game way. Especially religious aspects (and game is filled with symbols and allusions to Judaism and Christianity) such as role of god in human life, power of church among people or genesis of concept of God. Also you can find here lot of Nietzsche ideas and Freud and Jung theories. You can even find bit of Star-Wars-like elements what I find far less amusing (Lucas can go choke himself with EA) but I just try not to pay attention to it. Anyway it's surprising EA decided to publish such game. It's a pity it didn't became more controversial because maybe then all those Christian fanatics would by their own copy (so the game would sell better) to burn in public.
What I like mostly in Xenogears is its adult way to present things. There is quite a lot of gore in the FMV and love story between Fei and Elly is showed on many different aspects what make it a bit more interesting than usual. Also there is a bit of sex and nudity however don't expect to much. It's showed in very subtle way and leaves a far more for your imagination than eyes. Some quotes from philosophy or religion are not so obvious and you need to read a bit too so it's game that rather expect from player a bit more than just button mashing (however button mashing is also included).
Gameplay itself is rather classic. You walk on map, fight, buy equipment, go to the dungeon, and so on, so on. What make this more interesting are battles. There are two types - normal and with gears. The normal one includes button mashing in more extended way than usually. Every turn for each character you have attack points (maximum 7) which you distribute between light/medium/hard attack. Every attack have its own button so you create combinations of attacks. Some of combinations can after practice can become deathblows - special attacks that are essential if you want to progress in game. In addition you have abilities (or spells) for support and items. I find this system of mashing buttons to create attack chains very amusing and fresh from standard "attack? Y/N".
On the other hands Gears are a different case. They also have a special attacks but you need first attack normally to load energy for stronger one. There are several levels of those attacks that you receive with gears upgrades (gears don't get levels so upgrade is the only way to make your gear more powerful). Also every action uses fuel. You can restore a bit of it with special item (gears can equip special boots items that give them additional abilities) but still you need to plan your attacks more wisely. Also there is HP points for gear (that also can be restored whit special item but that uses fuel) and you need to look out for it because other gears can't repair you. Those fight are less amusing but still quite interesting (especially when you kick little monsters with giant gear). There is also special arena for gear fights where you can fight more freely; running around arena, jump and shoot street-fighter-like projectiles.
Xenogears is basically quite an easy game. If you don't screw anything and have good equipment most of fights will be piece of cake. I personally had problem maybe three times and it was only because not good enough gear equipment and lame strategy. However there is an element that will make you cry and want to kill everything in the room. There are few jumping sections in the dungeons where you need to jump form place to place and if at beginning it's easy than later you will thank God to have quick save/load on your emulator or curse your console for lack of it.
In the 1998 still fresh was impression that FF7's graphic made. That was another reason why Xenogears was ignored. It was made of 3D environment and 2D characters moving on it. It's not the most magnificent technical achievement on PSX console and many people weren't just impressed. Well what I can say is that now it looks far more better than block-shaped dwarfs on the rendered wallpaper. Maybe not to burn its beauty your eyes but feeling of freedom (you can move camera 360 degrees) and many little detail makes Xenogears, comparing to other PSX jRPGs, quite neat and solid from its technical side. Design is nice anime-like style but with enough dose of realism to not look like a child story (unfortunately cute talking animals are included).
Music is a different topic. Yasunori Mitsuda maybe didn't made OST of his life ( I still find Chrono Cross music better) but put enough of it's talent to make us all grateful to hid parents for bringing to life such talented artist. Melodies are very various in their mood and some of them remind Celtic or ethnic music. Voice acting is (because there is such) rather lame. Fei and Elly don't have bad voices but rest are very creepy. Lucky there aren't too many movies (well it's a pity on other hand because movies are made very nicely) and during game characters are mute.
I mentioned at the beginning that Square hurt Xenogears during its development. How it affected the game? Well if you will reach second CD you will see that many parts of gameplay were cut out and you can only read short explanation and screens illustrating situation. It's bit lame an take out a lot of fun however it don't affect the story too much so it's not so horrible thing. Still I would like to see those events by my own in normal way. Especially second CD because of that solution is like 15 hours long (first took me 40h). But I don't blame Tetsuya Takahashi and his crew for that (Square, you can Choke with Lucas and EA!).
To end this review I want to say for me Xenogears despite its imperfectness is my personal "game of my life". I didn't experience any other title that would move me so much, that would touch me so much, that would give me so much of joy, sadness or thrill from spending my time at the other side of the tv screen. Yeah, there are other games that are also magnificent and brilliant, and about which I can say that they are something more than just plain code, that they maybe have some kid of "soul". And if they really have, than Xenogears have the most noble and beautiful one.