The Caligula Effect: Overdose

Bought this on sale with no clue what it was and was pleasantly surprised by how interesting the cast and story were.
JRPG with the premise of what if The Matrix was run by Vocaloids
The battle system is... ok. It incentives juggling enemies to not allow them to get their turns but the lack of a battle timeline scrub control makes it far more time consuming that it should be.
MC stat improvements outside of levels is tied to the Causality Link which is a sidequest tree. Cool the first few times you try it, but with how much the sidequests repeat, gets really tedious.
I'd honestly recommend this game at lowest difficulty just to be able to speed along the story because that really is where it shines.

This game is kinda middling and mediocre in some areas, but the story was great. This version also gives you an option to side with the bad guys and I loved it. You end up fighting your party members and I've never see a game do it. That alone made this one worth playing.

It's a recommend if you enjoy JRPGs.
I can say that I genuinely enjoyed the story and the characters, it seems stereotypical at first but it breaks the mold and becomes something of its own. The characters that I didn't like were written to be despicable and the team behind game did so successfully.
The graphics are decent considering it was originally a PS Vita game (albeit in the very few instances of pre-rendered backgrounds resized to 1080p can be jarring). There are anime cutscenes that, while low-budget, are serviceable.
The gameplay is fun and strategic, with you inputing your moves and watching it unfold in a preview that you can go back to before letting it play for real and see if unfolds as planned. That said, the challenge is severely reduced after you reach level 50 on Normal (which should be halfway thorugh the game if you aren't avoiding enemies - there's no random battles - and clear the maps, as well some side-questing) so if you're an experienced player (i.e. the kind that actually uses buffs and debuffs instead of just mashing attack) then Hard should be more exciting.
There's three things that bring this game down to 7/10:
1) The dungeon design is nice when you go through them for the first time, but revisiting them feels repetitive, boring and unspired. Also, on a second playthorugh the Library and the Aquarium are genuinely annoying dungeons to go through again due to their gimmicks.
2) There are side-quests through the Causality Link system that raise your base stats - a grand total 524 of them, which means they're not unique and very repetitive. Hunting NPCs becomes annoying over time, involving revisiting dungeons after every story event, then clearing the quests available at that point can easily take an extra 5 hours or more between dungeons (and that's fast-forwarding the text or using the game's option to skip all of it). Also, you'll have a bunch of NPCs whose quests can only be done in the final dungeon, which annoying since you can't use warp points (or at least not before you fight the final boss and save afterwards) and running round the dungeons mechanically through the same path over and over again is just mind-numbing. I'm glad they carry over on New Game+ because I plan on never doing it again.
3) The Ostinato Musicians are very interesting and complex characters, but revisiting dungeons and having to fight mobs in order to raise their friendship level is just annoying and everything that isn't their story events feels like padding to justify the remake. Also, the alternative ending not only felt force but made me feel the biggest jerk in the universe (which would be fine if it earned it, but it didn't).
Finally, the highlight of the game: the music. It's simply excellent. The songs are made by famous vocaloid producers, but this time they had an actual singer (Reina Ueda, μ's voice actress) to work with and it's just amazing - the way it integrates with combat is very good too.
After 119 hours later and unlocking all the achievements (almost everything can be done in one playthrough, with the major decision that splits the two endings becoming available only right at the end; only two achievements require a second playthrough and New Game+ is available for that), I recommend it with the caveat that if you don't have tolerance for NPC hunting and fetch quests, stick to the main story (+musician's route).

horrendous gameplay, fantastic soundtrack and story. the musician route is a very unique idea and it's executed well. proof rpgs can only benefit from having an "evil" route.

This review is based on roughly 150 hours of gameplay time. I actually beat this game a few years ago, but just decided now to write my review. I have beaten the game on the hardest difficulty, Extreme and completed all character episodes, though there are still a few optional things I have left to do.
Storyline:
The Caligula Effect is a turn-based JRPG that takes place in a virtual world, Mobius, where people can escape from their real world problems by reliving their highschool years. You play as a group of students that have joined together to form the Go-Home Club. Their purpose is to escape Mobius and return to the real world, but they find out the creator of Mobius, the virtual doll Mu, is not allowing people to escape for some unknown reason. Furthermore, there is another group of individuals, the Ostinato Musicians, that want Mobius to exist and will fight anyone trying to interfere. You will also encounter digiheads, people who have grown so dependent on Mobius that will fight anyone that causes a disturbance.
The characters and the storyline left a strong impression on me. They definitely rank up as some of the best in the many rpgs I have played. The game does a great job of drawing the player into the world and making them care about each of the characters. They all have different reasons for wanting to leave or stay in Mobius and many of the characters are also not what they appear to be on the surface, but that's all I'm going to say on that. Try to avoid spoilers when playing this game, if possible. The events of the storyline definitely surprised me on more than one occasion.
Battle System:
The battle system is one of the strongest points about this game. The game is turn-based, but actions have startup time, active time and recovery time. For every character turn, you can chain up to three actions. A particularly interesting aspect of the battle system is what the game refers to as the "imaginary chain". When you select an action, the game will play a preview of all actions that have been selected or were already playing out, including the enemy actions. If you don't like the outcome, you can select a different action instead or even modify the current action to changing the targets, positioning and even adding a delay. This allows you to plan things out in advance before committing to the actions, but there is one important thing to consider. The imaginary chain assumes that all actions have a 100% accuracy, but your actual actions when committed to, will not. As a result, if one of your actions do miss, then the outcome of all the actions you have queued up for your characters will be very different than what the imaginary chain had projected they will be.
As for the kinds of actions available, there are a wide variety, which vary based on number hits, startup time and recovery times. Some actions can have additional effects such as launching or knocking down the enemy, guarding attacks, breaking guards, causing status effects and inflicting buffs and debuffs. Some actions are available automatically for all characters, such as the dashing and emergency barrier. Others are learned in the form of skills, which require skill points to be unlocked.
Difficulty:
The game offers 4 difficulty levels - easy, normal, hard and extreme. Hovering over extreme difficulty gives the following warning: "Do not select this. You will immediately die in battle if you aren't paying attention". While I agree that it is very hard, the problem is that the difference in difficulty between hard and extreme is massive. For even an average gamer, hard mode will feel relatively easy. Since I'm a gamer that prefers to play games on the highest difficulty, I decided to beat the game from start to finish on extreme. It was definitely a massive struggle at first but became manageable once I became familiar with the mechanics. Just be warned that boss battles are especially difficult on extreme and will feel like a massive roadblock, since you can't progress the story without beating them.
Causality Link:
This game has a social links system that somewhat resembles the Persona games. By completing a character's "episodes" when they have an exclamation mark over their head, you can increase your relationship with them and uncover their backstory. It is advised to complete these episodes the moment they are available, or they will be missed. It is also important to know that if you respond to the choices provided incorrectly, you can lock yourself out of the character's remaining episodes. Luckily, the game tells you immediately when this happens, so it is best to save right before doing a character episode and then reload if you mess up your responses. I highly recommend reading the walkthrough on Gamefaqs by the user MaySarton, following it exactly will ensure that you don't miss maxing out these character relationships. This guide also does a good job of not spoiling the events of the story.
There is another aspect of the social link system, called the Causality Link, that probably deserves the most criticism. There are over 500 students that you can find and befriend. Not all of them can be befriended right away, as you may need to become friends with their friends in order to talk to them. Each is suffering from a psychological trauma and once you've become their friend, the game will tell you what needs to be done in order to cure that trauma and receive a reward. The problem is that many of the interactions and dialogues of these students are copy and pasted. For example, there may be 5 different students with the Imaginary Friend Syndrome. Each one of them, say exactly the same thing, word for word. It is clear that no effort was put into this aspect of the game. With that said, 500 students each with their own problems to resolve, can become tedious and repetitive, though at least this part of the game is completely optional. The rewards are equippable passives (for all characters) and permanent stats for the main character. While they may seem minor at first, the stat growths for the main character do stack, and help greatly with overcoming the game on extreme difficulty.
Audio and Visuals:
The soundtrack is high quality in my opinion. Each musician character in the game, has their own unique song that really captures the essence of that character.
Regarding visuals, the character model quality is average at best. A lot of the models are also reused, particularly for the students and the digihead enemies which you will be encountering constantly throughout the game. While the character models aren't that great, the art for the character portraits and their poses in the status screen are very well done. For me, the visuals didn't really have any impact when it came to evaluating this game.
Conclusion:
This is an amazing game if you enjoy action/turn based rpgs. While there are definitely valid criticisms regarding certain aspects of the game, especially the Caustality Link system, I think they are greatly outweighed by it's strengths, which are the battle system and unique storyline. Unfortunately, I feel like the review scores this game receives on Steam, as well as review sites such as Metacritic, are lower than the game deserves.

great ost and a story that makes you think and keeps you hooked with unique gameplay mechanics and interesting characters.

Get this game if you want a JRPG with unique battle system, amazing character design, lovable cast of characters (even the antagonists!) and banger OSTs.
There are a some downsides that I encountered, such as stiff animations, repetitive dungeon design and I feel like some of the story lacks the resolution that it deserve.
My mind has been occupied by this game for weeks now, you can say it's all the effect of overdosing on caligula, heh.