A Doom 2 fan has discovered the game's final secret nearly 24 years after its release, winning praise from the series' co-creator.

A player going by the name Zero Master posted a video on YouTube -- first reported by Rock, Paper, Shotgun -- revealing how to unlock the secret in the first-person shooter's 15th level. This was previously thought to be impossible due to a bug.

Triggering the secret requires a player to draw an enemy to an area -- in this case, a Pain Elemental. The enemy would then push the player onto the secret and trigger it.

Experts have known the location of this secret, but couldn't access it without cheating… until now.

"CONGRATS, Zero Master! Finally, after 24 years! 'To win the game you must get 100% on level 15 by John Romero.' Great trick getting to that secret!" co-creator John Romero wrote on Twitter.

"Secret explained: A secret teleporter is marked as a discoverable 'secret', but when you touch it, you never enter the sector. So you would never get inside the teleporter sector to trigger the secret. The only way to trigger this secret is to be pushed by an enemy into it!"

Doom 2: Hell on Earth -- the second in the iconic franchise -- was released on Sept. 30, 1994. The series was rebooted in 2016 and the next game, Doom Eternal, was revealed at E3 and its gameplay was showcased at QuakeCon in August.