I really liked 13 Sentinels: Aegis Rim. Of course, that has to do with it being a Vanillaware game as I do have a soft spot for the studio's output. The audaciousness of the concept and its story is pretty alluring on its own though.

Here is a game that seems to be a Japanese visual novel with a hunger for 80s nostalgia, mixed with a light strategy role-playing game, and topped off with a Wikipedia breadcrumb binge. It's perfect in none of those categories, yet this weird mix seems to work in the end, jaw hinging slightly ajar.

Spoilers ahead.

The Good

• Story-wise, I was genuinely surprised at the overlap in setting between this and Horizon Zero Dawn. Not that these two games are the only titles discussing a post-post-apocalypse setting, but both envision a future where humanity as a whole lost, went into hibernation as a last ditch effort, and finds adversaries in the very tools that were designed to help them.
  Where Zero Dawn fails for me, is that the setting's origin is almost freakishly more interesting than the actual plot of the game. 13 Sentinels does not have this issue, instead the setting is the plot and grafted into the characters' actions as a whole. Zero Dawn has, in comparison, a large divide between plot and setting, with Aloy forming the sole lynchpin holding them together. It kind of works, but it makes it very hard to care about anything beyond the core mystery. This is emphasised by her outsider status in more ways than one. Unfortunately, it means the rest of the world can go to hell for me as a player. The only incentive there lies with Aloy and the actual Zero Dawn.
  Whether intentional or not, 13 Sentinels doesn't touch the 'what happened after' part at all. It squarely focuses on the connection between the characters and the world they inhabit. Everyone is an Aloy here, almost verbatim. And instead of being told what happened, you're experiencing it first-hand, while not being entirely clued in that you are. It makes for a delightful puzzle (I — quite wrongly — thought I had the story figured out at least five times during the course of the game) and makes sure that every aspect of it adds to solving it. It was the video game equivalent of Netflix's Dark. In comparison, if you take away all the extra tribes and people in Zero Dawn, and are just left with Aloy, the machines, and the mystery of Zero Dawn itself, then I'm quite positive the game would be just as enjoyable. Maybe even more so. Regardless, I feel 13 Sentinels nails this particular aspect and provides and maintains interest throughout its entire runtime. Or, as Dirk Gently would have it: "everything is connected".
• The combat reminded me of Dungeons & Dragons in that battles take about 2 minutes according to the mission timer, but taking actual turns expands this tenfold in real time.
• You can tweak the hell out of the visual novel settings in terms of subtitles and voice work. Spend a few minutes setting it up and the visual novel part can act and feel like an experimental anime.
• The game has a tendency to present you with far-fetched concepts that add to the general weirdness, only to dispel them and replace them with even harsher in-game realities and make them all part of the plan. Granted, some instances work better than others, but damn. That's good.
• By ye gods, does this look fine. Even the radar graphics during the strategy RPG parts have their charms.
• While Dragon's Crown's insane body proportions raised more than a few eyebrows, 13 Sentinels seems to me a lot more self-aware of what it's presenting. Yes, you do see a young woman caress her thigh to summon a giant mecha within minutes of starting the game, but by the end of the game it has earned the right to use that scene and call it logical. Kind of.
  It won't please everybody, but I did get the idea the game is trying to display teenage insecurities instead of just throwing around some skin. That said, you could argue the game is pulling a 'Quiet' where the cockpits are concerned, but even that is allowed to make a whole lot more sense in comparison. YMMV.

The Bad

• The thought cloud concept was interesting, but also a bit of a failure. A subject being mentioned can trigger them as conversation topics for internal monologues and external dialogues. Unfortunately, that never amounted to anything more than providing additional information. That in itself is not problematic, as the game's currency is basically information, but it means there's zero challenge in the visual novel elements. It's exhausting all options without consequence. Feels like they missed a potential trick with this kind of setup as the branches in the storyline are merely options as well and don't require much insight or cunning.
• Combat could use some additional balancing. The game is a bit on the easy side and even provides an easy mode — which isn't bad, actually. The problems are with the upgrades available when levelling up. There are a lot of them, but considering the simplistic radar-like presentation of the game they don't feel very different or amount to stat changes. The game practically plays itself when you unlock the Sentries and unintentionally turns the actual game part of this game into a slog. I guess it does fit the Vanillaware tradition of making one combat thing work and repeating it ad infinitum.

The Ugly

• If you're not used to Japanese, the cast of characters and their names are going to be a nightmare. Even if you are used to the language, thirteen protagonists and a whole host of supporting characters means you will drop the ball at some point. You may want to keep a notebook nearby.