This isn't really a walkthrough on how to beat the whole game level by level, but some basic tips and some info on the enemies that I have gained from experience. If you have any questions that you feel did not get answered then ask.
*Tips*
*Combo moves are key to victories against enemies. There are six different combos, the last one being the most important. When you unlock them all you'll have much better control over the battle with all sorts of moves at your disposal. When you unlock swift kill, the last combo, use it on every fallen enemy, especially the harder ones. Use this in conjunction with the Running Attack and Lift and Kick combos.
*Bombs are powerful, so don't waste them. Save these for bosses and harder enemies that can take lots of damage.
*When a new weapon is available, be sure to buy it. The weapons get better with each hide out you reach, so always be sure to buy the latest updated weapon. Towards the end of the game, the weapons will stop taking stats from certain areas like speed, armor and strength and start adding them instead to all three of them.
*The best way to deal with an oncoming ninja star is to melee it back at the enemy who threw it. This will knock them over, deal damage, and keep you safe from harm.
*List of Combos*
Running Attack: This is great for knocking over enemies and also dodging incoming projectiles. Be sure to follow it up with swift kill to instantly eliminate any tough opponent.
Lift and Kick. This one is also good for knocking enemies over and dodging projectiles. I found myself using it a lot for both of those purposes, and also because it looks flashy.
Windmill: This one is cool, but not very powerful. It's good if you want to stun enemies though.
Grinder: A powerful and brutal attack, but leaves you vulnerable because of its slow execution. I found myself using this one more on accident than not on accident.
Backflip: Great for surprising and enemy behind you. It also knocks them over to. You can also use this to dodge incoming projectiles.
Swift Kill: I love this one. The game will be so much easier when you acquire it. Just knock an enemy over with a simple combo, then press A or S over their fallen body to finish them instantly. Great for tough enemies.
*ENEMIES*
Basic Enemy: These guys suck, they have no combos, no ranged weapons, basic swords, and little health. Finish them quickly then collect the easy loot.
Basic Samurai: These guys have a few combos and more health, but their not to much harder then their basic counterpart.
Assassin: These guys are a little trickier, their faster, have more combos then the basic samurai, and can throw shurikens. Eliminate them first in a crowd of enemies.
Armored Samurai: These guys wear all red, have bombs, lots of combos, and lots of health. Their tough, but they can be defeated if you're good at dodging and have your swift kill combo at the ready.
Swamp Creatures: These guys are a little tough. They can slash, they have long tongues that stun you, and projectiles slime goo. Tackle these guys one at a time, and never battle one in front and one behind. Total disaster if you do.
Oni Caverns Monsters: These guys are fairly easy, except they have fire balls and swords. I'd suggest ignoring the Oni Caverns all together until you have really good weapons and a high level.
*BOSSES*
Tower Boss: These are basically basic enemies in towers with bombs. Sounds hard, but its not. Just slash at them at the right time and watch for the shadow of the bomb they just chucked at you. Move safely out of the way, let the bomb explode without harming you, attack again, rinse, repeat.
Slime Monster: This guy is easy. Watch out for the big swamp bubbles, strike at him when he comes out of the swamp as much as you can, then move out of the way when he starts to vibrate.
Cave Monster: This one is easy too. Slash at him a bunch when he roars, then move out of the way. Be careful of his trample attack and his kicking hind legs and you should defeat him in one try.
Samurai Boss: These guys look really intimidating. Huge, spikes all over him, and two giant swords. He's actually really easy. Just dodge him when he strikes and always try to be behind him when he does his combos. Should you be on the front side of him when he does his combos, your in for a huge loss of health.
Evil Samurai Master: Luckily, no minions as far as I know come to his aid. To tell the truth I still have yet to beat him. All I can say is make sure you have the best weapon, high stats, all combos unlocked, and a healthy supply of shurikens, bombs, and health potions. Your attacks do barely any damage to him, and he's fast.
If you have any other questions just ask.