As long as you keep that content warning in mind, I can't recommend Tokyo Jungle enough. The violence shouldn't have been surprising, but the clever structure of the game is a well-earned surprise.
Tokyo Jungle uses two parallel progression systems, in two different modes. The "Story Mode" is sort of a side story to the "main" mode, Survival, which runs counter to what I would expect. Story Mode is a series of scripted stealth missions each telling a portion of a certain animal's life story, like a Sika deer looking for its mother. These are at once silly (you can wear a giant box like a four-legged Solid Snake to get by hyenas) and heartwrenching (your sibling sacrifices itself so you can get away).
But you can only unlock each Story mission by picking up "archive" items – documents that reveal, in pieces, the story of why all the humans are gone – in the main Survival mode. However, picking up archives is only one small goal among the many concerns you'll be dealing with.
Survival mode is also where you unlock new animals, level up the ones you do have, and pick up new clothing items. Keeping your "hunger" meter filled by continually eating, your animal explores a section of Tokyo that is crumbled and overrun by other animals. If you eat enough, you level up to "veteran" or "boss," which allows you to attract a mate once you've marked enough territory in each part of town. Leveling up increases your stats, like HP, stamina, hunger, and power, and mating passes some of those traits on to the next generation.
This is also the only way you get to save your game, and the only way you can make permanent changes to a certain species' stats. Once you die, you're dead, but you can start over with the latest "generation" of animal you've achieved. There are some roguelike ideas at play here, in the odd interaction between permadeath and incremental upgrades over multiple playthroughs.
Aside from just surviving, you're also encouraged to complete timed challenges that pop up every ten in-game years or so. These "achievement" like challenges range from simply going to a certain location, to killing a certain number of animals in a certain way, to defeating a "boss" animal to unlock that variety of creature in your own playthroughs. The dynamic creates a tension between various goals: do you go south to Shibuya Shop District to pick up archives, or do you go north to complete a challenge and upgrade your cat?
Even then, there's another parallel mode of progression: finding new animals makes it easier to complete challenges, as you can unlock larger, stronger, faster animals. A retriever can deal with hyenas a lot better than a Pomeranian can, for example.
All the interplay between these various mechanics offers a depth and complexity I wouldn't expect from a game about dressing up a small dog in a ninja suit to increase its survival skills.
The base moment-to-moment gameplay is exciting as well, providing a reason to participate in this metagame. It's a sort of Final Fight-style side-scroller with stealth and light platforming. As a carnivore, you attempt to sneak up on animals by hiding in grass or just slinking quietly, then pounce. If you succeed (and you're not a housecat trying to take down a hippo) you get a one-hit kill. If you're spotted, you have to fight with claws and teeth to take the prey down – the same mechanics you'll use, along with dodges – to defend yourself from attacking enemies. As a herbivore, you fight only to defend yourself, and subsist on plants growing up through the cracks in the road.
Sometimes, you won't have much luck defending yourself. And by "sometimes" I mean frequently. There's not much to be done when you're starving and you wander into an area where the only animals within sight are a pack of lions, who have just spotted you. And there's toxic rain falling on you. That's just nature taking its course, in Tokyo Jungle's exaggerated way.
This article is based on a pre-release PS3 version of Tokyo Jungle, provided by Sony. Tokyo Jungle will be released through PSN on Sept. 25, for $14.99.