Back in the days of the original Crash Bandicoot , a GameShark code could grant players access to Stormy Ascent. It was a level that Naughty Dog ultimately left on the cutting room floor. The level was extraordinary difficult and also home to several bugs, so it wasn’t possible to prepare it in time for release. Now, developer Vicarious Visions has posthumously completed Stormy Ascent and added it to Crash Bandicoot N. Sane Trilogy as post-release DLC.
In the original version of the Crash Bandicoot N. Sane Trilogy level, collecting the Cortex Tokens would increase a rate of screen-freezing. Collecting all three would ultimately cause retail copies of the game to crash, due to no actual bonus level existing. In the remastered version, Vicarious Visions designed a new bonus level, and the game adds an extra 2% bonus to your overall completion for finishing it, as well as making the number of gems 27/26.
Crash Bandicoot N. Sane Trilogy is already a challenging game, especially thanks to some physics issues. Players able to complete Stormy Ascent and complete it 100% will have quite the bragging rights. For the next 30 days, the Stormy Ascent DLC will be free to download. No word on how much the level will cost after the grace period.
Source: Bandipedia