A new top Geometry Dash extreme demon was verified by Zoink on June 7, 2023, called Tunnel of Despair. Made by Exen and ImMaxX1, it is heavily wave focused, according to one source.
According to Zoink, it might place in the top 20-30 on the Pointercrate Demon List, the most popular ranking of Geometry Dash's hardest levels. According to Exen and ImMaxX1, it is a top 10 hardest level in Geometry Dash.
I personally see this as a top 15-20 hardest demon, but take that with a grain of salt as I am not a skilled player.
Its decoration is styled like Unknown, a particularly grey extreme demon, but Tunnel of Despair mixes in a bit of red. It looks cool and has some good sync. While probably not the best extreme demon, it is certainly worthy of being rated by RobTop.