Just played the first level of the demo. Goodness, that took a while...and around 50 deaths. They definitely need to port it over to the iOS. It's some pretty awesome platforming fun.
Back in the day the platformers on the original NES were very difficult. There were no Saves for the most part. Some that come to mind are: Ninga Gaiden and Ninja Gaiden 2 (NES) IKari Warriors (NES) Commando (NES) Rambo (NES) Gun smoke (NES) Rygar (NES) Gradius (NES) Magician Lord (NeoGeo/Arcade) There are so many more but these are games where u died and died and died over and over to the point u were hurling the controller at the screen. Recently Beowulf for XBox 360, Assassins Creed Altairs Chrinicles on iPhone (I died a thousand times trying to make the jumps with the touch controls) And Demon Souls for PS3 was evil hard.
Eliss is an impossible but great game that very few people have ever finished I gave up around level 15 of 25
Took me months to beat Ninja Gaiden. Had to memorize the entire game, and even then it was crazy hard. You can also add some old shmups like R-Type and Gaiares. Demon's Souls was also super hard but one of the best games I've ever played, had to Platinum it twice (American and Asian version). Awesome game.
i found bit trip beat quite hard..and frustrating when it used to make you start from the beginning. also have been trying to beat r-type on various devices for the last few years.
JuBeat... Try to do any difficulty other than basic... I can barely get a passing mark on intermediate, and I play the piano.