This is a notoriously difficult and merciless game. Do you know someone who constantly whines about how easy games are nowadays? Put them in front of this game and don’t let them leave until they’ve beaten at least two levels. Some games are difficult just because they throw a bunch of things at you at once or make you react quickly. This game is actually pretty brilliant (read: sadistic) in its difficulty design. It knows just what you’ll want to do, just where you’ll want to jump, and it will put something terrible waiting for you in that perfect spot. It trains you through pain and mental anguish. Even on Casual, its still pretty challenging. Did I mention it has a fake ending? That’s right, beat this game and you’re rewarded with an ending that tells you this was all just a trick of Satan. Now you have to go through the entire game again. This is pretty much Demon’s Souls' great grandpa.
Is it fun though? I’d say there is a lot of enjoyment in finally learning the pattern in games like this. When you know where to jump, when to wait—when you’ve finally got the map memorized and you’re in the zone, that’s when these kinds of games get to be fun. That’s not necessarily the definition of fun in games nowadays, but it is a pretty pure and classic form of gameplay.