the most insane level ever! is the 41st level in David Stolp's pi.dat. This was the first insane level ever created, having been released on July 3, 2003, and introduced the concept of data resetting. the most insane level ever! is almost certainly the most well-known insane level of all time, possibly the greatest, and definitely one of the hardest.
The solution of the most insane level ever! has been made into an AVI, although it was never uploaded to Anders Kaseorg's or Mike L.'s AVI libraries; it is likely this was originally found in Muppetlabs during the time period where this was used to exchange AVIs.
