Saw someone raving about this on the forum the other day, comparing it to the likes of BOXBOY! in terms of being an underappreciated gem on the 3DS eshop. It was only $4, so I decided to give it a go. For that price, it's not too long (took me 2.5 hours), and it's not a bad Metroidvania.

There's basically zero story. Tengu captures princess, you try and defeat him, but get kicked out. You've gotta go collect Metroidvania equipment upgrades and subweapons to be able to unlock the door to his castle. I wouldn't say the theme carries as much in this game as in the Metroid or Casltevania games though. Perhaps that's due to lack of story, but I just felt the Ninja theme wasn't that memorable (sans the Kappa Tank, which was a great boss).

It's a straight up action game. Go around the map, occasionally collecting health upgrades. The game uses a Portrait of Ruin-style map where the overall world is fairly big, but there are doors which contain full-dungeons around the map which is where most of the upgrades and bosses lie. You have a sword and several subweapons, but your sword is what you'll mainly use. Once you get the double jump fairly early on, you can slash enemies in mid air to get extra jumps as well, which calls for some tricky platforming occasionally. The jumping is so crazy once you get the Ninja Gaiden-style wall cling, that I actually found a fairly neat sequence break that allows you to skip the 3rd to last dungeon (the ice one) if you're good at triangle-jumping.

The normal enemies aren't too thrilling, but the boss battles range from pretty good to really great. You can also carry quite a lot of potions which you can buy with gold enemies drop, so the game is more or less as difficult or as hard as you want it to be with how you'll limit your own potion use (much like the DS Castlevanias, imo). My personal favorite boss was the aforementioned Kappa Tank. I had far more fun against him than the final boss (even if you can more or less kill the bosses fairly cheaply with an early item). Dodging and just using your sword was the most challenging and fun way I found.

Verdict: If you're REALLY worn out of all of the Metroid and Casltevania games on DS and GBA, then this is an okay thing to tide you over. It's certainly one of the best non-Nintendo or Konami Metroidvanias I've ever played, but I'd frankly hesitate to put it above even my least favorite Castlevania game not only because of the fairly short length of the game, but more so becuase of the lack of combat depth.