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Samurai II: Vengeance is a great title developed by MADFINGER Games, powered by the Unity engine. It's a great hack and slash action game with a jaw-dropping art style, and it's definitely worth your money. It isn't perfect, though.
The story plays out in some very well drawn comic book pages. You are a samurai hunting for a demon warlord dude named Orochi. I can't say if the story is a continuation of the first game, as they didn't bother porting that one over from the iPhone, though the story is easy enough to follow, and apparently the sequel is far better than the original anyway. Your mission is to hunt down and stop Orochi, cutting down all who stand in your way.
The controls are split into a movement stick and three buttons: light attack, heavy attack, and dodge roll. As you move through the levels, you will happen across combat areas and magical floating padlocks will keep you in that area until you kill everything that spawns. Sometimes you'll regain your health after these fights, and sometimes you won't; it's quite random. The rest of the levels are populated with random hazards, like spinning blades or swinging axes. As you kill enemies you will gain Karma points, which can be used to buy upgrades. You also get karma points from destroying the barrels that litter each level. To upgrade, you just tap the health meter in the top left. I recommend you upgrade your health as soon as possible. You can buy new combinations, but you have to upgrade them twice each to get the full attack. It's kind of annoying really, as the combo doesn't help you out much until it's complete. Pulling off combos in this game is simplified thanks to your hit counter, which also displays what buttons you're pushing. It's really helpful. The controls can get in your way though. I feel like the buttons are too close together, and I'll often hit the button right next to the one I'm actually aiming for. You can move the cluster of buttons around, but you can't move them apart.
The action here is fantastic. You hack and slash enemies to bits, and whenever you score a critical hit, you execute them regardless of their remaining health. You will split them clean in half either vertically or horizontally, or you might just decapitate them. The game is bloody and glorious, and blood will even spurt across the screen. I love it. I don't understand how the critical hits work exactly, if they are completely random or if you set them up somehow. Sometimes I'll do two or three in a row, which is very helpful in the later game, but it isn't consistent. The campaign consists of seven levels. I recommend you start off on Easy mode. I started on Normal and had a lot of difficulty. There is also a Dojo mode, which is like an arena challenge with progressively harder fights.
This game is absolutely gorgeous. I love the art style, which is very reminiscent of games like Okami. I just can't get over how aesthetically pleasing this app is to look at, but that might just be me. The combat is fast and furious, and I had a lot of fun with it, even though I died constantly. The yellow guys that spin around with their swords can burn in the deepest levels of hell. This app is about $3 and I highly recommend it.