This is just some gameplay footage of Ninja: Shadow of Darkness on the PS1 as played on a PS2 with texture smoothing on. I just recently got this, and only just fired it up today. I had played the demo previously.
This game comes from Core Design of Tomb Raider fame, and in typical Core fashion, it's a hard game that requires quite a bit of patience.
I browsed the Gamefaqs user reviews of the game, and most of them were complaining about the difficulty. The controls can be tough when mixed with the static camera angles and when mixing in platformer elements, but the game also has cheap deaths, and a set number of continues. Luckily, it also supports memory card saves, so if you make good enough runs in each level to keep your continues, you can just reload your game instead of continuing. Granted, the continues start you out at your last checkpoint as opposed to the beginning of the level like the saves do, so constantly reloading your game can mean having to play through the same level over and over again. While, yes, having a mere three or four continues is a cheap way for the developers to give more life to the game, those with an old school mentality are used to replaying levels in games over and over again. I haven't made it to the later levels yet, and I'm sure they are really tough, but Ninja is a game that requires old school patience to play. Most gamers probably won't like this game, but if you can't win...cheat.
I haven't played that far into the game yet, but even with the difficulty, I'm really enjoying this game so far for some reason.
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https://www.youtube.com/watch?v=fCQCAIGZm_U