Around and about online, I see a lot of talk about Riviera being an "innovative" RPG. The thing is, though, it really doesn't introduce anything brand new. Instead, what it does is take a whole bunch of elements from other RPGs and shuffles them up in a new way. It's a pretty unique and complicated game, so we'll get around to all those borrowed elements bit by bit. Let's start with the introduction and basic story of the game to begin with.
OK, so the forces of Ragnarok are threatening the land of Riviera ... or wait, maybe it's the forces of Asgard threatening Ragnarok ... actually I'm not sure because the really slow paced introductory sequence kinda made me doze off. I guess it doesn't really matter, because you can pick up what you need of the story as you play the game. It turns out that we are playing as a kid named Ein who is a "Grim Angel" sent to destroy all these evil demons that are apparently running rampant or something ... but to do this I guess for some reason they have to activate Tactical Nuke that blows up the land of Riviera while they're at it. Despite the gothy name the "Grim Angels" actually look more like Pokemon trainers than anything else, and the whole game has the tone and dialogue level of a pre-teen Cartoon Network anime. If you've played the Lunar games or Tales of Symphonia, you'll recognize a lot here because those are the two games it draws most from for it's character designs (right down to having a taking flying cat familiar a la Lunar, and having the characters give a little speech and yelling out the names of their special moves when attacking a la Symphonia ... you've even got pervy hidden "bathing scenes" lifted straight from Lunar).
Anyway, Ein starts out on the side of the Magi or whatever, who are like the religious authorities. It becomes clear pretty early, however, that the Magi or the Grim Angels or whatever are more like religious maniacs and generally unpleasant to be around, plus it sounds like their leader Hector is up to some unsavory shiz involving "reaping souls". And Ein isn't completely convinced that blowing up Riviera, which is basically filled with the people they are supposed to be protecting, is the right thing to do. He and his partner cut their way through this ancient ruin that is supposed to lead to them backing up in that ass with the Retribution or whatever, but Ein gets knocked out during a battle with a mysterious woman and teleported down to Riviera, losing his memory in the process.
It's actually not that bad of a concept for a story, but there are a couple of major problems that really hold it back. The first is the structure of the game, which is pretty unorthodox. It's divided up into seven stages, with sub-levels like Ninja Gaiden (1-1, 1-2, 1-7, etc.). Each of these stages is basically just a giant dungeon of some sort, and there's only one town in the game which you take short breaks at in between stages. So you basically spend at least 80% of the game's playtime fighting your way through dungeons, which means the world that you inhabit is not very fleshed out and thus doesn't feel substantial, and therefore it's hard to care a whole lot about what's going on storywise. It actually wouldn't be too inaccurate to call this game a "dungeon crawl", really. The game also teases you with it's introduction, which seems to indicate you may be getting a poignant and darkly beautiful story ... but what it actually ends up being is more like goofy Naruto-esque anime that has so many elements from other games airlifted into place, it's hard to get really involved in (unless you're a schoolkid who is into the Cartoon Network anime, in which case I'm curious as to why you're here and not over at GameFAQs).
Anyway, each level basically consists of a handful of screens. Usually you're just passing through and fighting monsters along the way, but occasionally there's some light puzzle-solving such as finding your way through a Lost Woods-style maze. Usually, once you leave a level you can't go back, though occasional plot events will kick you back to a previous level temporarily and you'll have to work your way forward again. You are never able to return to the overall stages once they are completed, however.
The battles are unlike any other RPG, yet they use elements from many of the most famous. First of all, they are all pre-set and monsters don't respawn, though you usually do not see them coming and cannot avoid them. You can bring three characters into each battle, and up to four items (out of a total inventory of about fifteen). Characters have stats, but they don't level up or equip items in the standard RPG style. Instead, each weapon or item does a certain attack or casts a certain spell depending on the character who uses is. To "level up", certain characters gain "experience" with certain items simply by using them. Once they've used an item in battle the requisite number of times, they get an "overdrive" move with that item, and also get a small stat gain - this is the only way to increase your stats in the game, other than the occasional random dungeon event that may raise or lower your stats a little. The catch with items is that they have a limited number of uses, and break once they are gone (and most cannot be replenished). However, there is a Practice mode (accesible on almost any dungeon screen) that allows you to fight a battle with a previously vanquished foe, in which any items you use will not degrade at all. The battles kind of resemble Ogre Battle in their isometric perspective and control - they are turn-based, but each item and attack will only hit enemies in a certain row, or may only target enemies that have the highest or lowest hit points of the group.
Confused yet? Just wait, it gets even better. Moving around is also unorthodox. You can move from screen to screen in the levels pretty freely, but in order to investigate items on each screen (such as treasure chests and hidden passages) you have to use "TP points". You are issued a small amount of TP points at the beginning of each stage, and gain more by winning battles - and the stylishness with which you win a battle (for example, by using an Overdrive as the final blow and ending it in as few turns as possible) determines how many bonus TP points you get. If you don't have TP points, you don't get to interact with the environments and thus can't find any cool bonus stuff (also, Practice battles do not grant you TP, you can only get them from the limited amount of "real" battles on each level). Every now and then, outside of battle, you also come across a sequence that resembles the mini-games used in Final Fantasy X's Overdrive attacks (stopping a sliding bar at a certain point, pushing buttons in sequence, pushing buttons in a certain rhythm ... see also Shenmue, Dragon's Lair and Parappa the Rapper). These are used to disarm traps on treasure chests, or to determine whether or not something nasty happens to you.
The art style strongly recalls Final Fantasy Tactics Advance. Normal overworld, dungeon and battle sprites are pretty smushy and look like the typical uninspiring GBA strategy-RPG, but there is some very nice background art and the game frequently uses nearly full-size character portraits in the story.
The game's art is very nice, but one thing you will quickly notice is that there is very much a ... um ... "Loli" theme running through this game. Almost the whole of Sprite nation seems to be composed of winsome females that look like eleven year old girls ... and they also happen to mostly be wearing very revealing outfits. It's so pervasive that the game seems to be fixated on the sexuality of adolescent girls (that step very close to the border of pre-pubescent in some cases), and as such it's really a little disturbing at times. Of course, if this sort of thing is your bag, *shrug* ... I guess I'd rather have you jerking off to your GBA than showing up on that "To Catch A Predator" show or whatever.
In a move that I'm sure will further please the Pedobears out there, the game has ongoing "dating sim" elements. Ein travels around with a harem of four female companions, and the choices you make in certain conversations with them affects their affection towards you and which one you eventually hook it up with in the end, I guess (I haven't finished the game).
Riviera is definitely interesting. Unfortunately, it's also tedious in a lot of ways, and doesn't really have broad appeal. The game was really designed with a particular subset of gamers in mind - compulsive level-grinders who also happen to have Lolita complexes. That's actually a fairly substantial portion of console RPG players out there, just enough to make games like this profitable at least. But it's not really going to appeal to anyone beyond that group.
The battles have just switched out the traditional set of repetitive mechanics for a new set of repetitive mechanics. Instead of grinding for EXP on random enemies, you grind by using the same items over and over in meaningless Practice battles, which in many ways is even worse than traditional RPG grinding. They also commit a cardinal sin of gaming - taking too much control out of the players' hands. The game gives you all these cool items and battle abilities, but instead of letting you play with them it imposes extremely tight restrictions on you - only four per battle, and only fifteen in your overall inventory at a time. You are constantly throwing out items that you'd really like to keep and use, and letting cool stuff gather dust because you don't have room for it without sacrificing necessary basics of your battle item set. And battles require too much pre-planning just for simple details, like "does this characters weapon hit enemies in the front or back rows?"
As mentioned before, the game is also about 80% dungeon. There's still a lot of plot development despite that, but the pattern of going through a long dungeon and then briefly returning to the same town over and over again lacks variety and gets quite tiresome after a few hours of play. Though the dungeon settings change, and you get new items, you still feel like you are basically just repeating the same motions over and over and over again. Frankly, I got about 75% of the way through the game and then dropped it; I just couldn't muster the enthusiasm to go through the last couple of dungeons. It just wasn't enough fun.
Likewise, the "TP" system really should have just been dropped. It doesn't add anything to the game, just creates another restriction on the player and makes progression choppy. And the game is way too obsessed with ranking you, giving you a grade on every single battle, rushing you along to do everything in as few turns as possible, even grading you on how well you've pleasured the ladies at the end of each chapter. Again, this is something obsessive-compulsives might enjoy but everyone else will probably just get fed up with it and wish for some more freedom to just play and explore and have fun.
I dunno about Riviera, buds ... I appreciate what it's trying to do, which is to fix the boring/broken conventions of standard console RPGs, but it just doesn't really seem to do it *right*. It tries to streamline the action and improve the pace, but at the cost of depth and ability to control what's going on. It excises long boring cutscenes, but we still have the same generic anime setting with plot elements lifted from nearly every other game/anime ever and childish characters ... it also excises long slow-loading battles, but at the cost of making them oversimplified (again with the control issues) and so limited as to be tedious and repetitive. It'll work for some people, but I suspect there will be just as many for whom it won't.