Secret levels in Lode Runner: Lost Labyrinth (1990)

Lode Runner: Lost Labyrinth is an obscure version of Lode Runner for the PC Engine developed by Pack-In-Video, overshadowed by Hudson Soft's Battle Lode Runner for the same platform.

The game ostensibly only has 84 stages, but buried in the comments of an old YouTube video and seemingly not covered anywhere else reveals there are actually stages up to 112.

The graphics in these secret stages look different and unfinished as if they are from an earlier stage of development of the game.

After you beat stage 84, an end screen appears. During the end screen, if you press the I and II button simultaneously while pressing up, it takes you to the 85th stage.

There is one caveat in that there is a bug on stage 97 that will prevent you from finishing that stage. Therefore you must skip it with a password.

After you beat stage 112, you get a different ending which shows off all the enemies in the game with their names.

The password for the 84th stage is "1922-6098-0408-6485", 85th is "9834-1529-7765-1704", 98th is "1511-1046-5513-8425" and 112th is "3699-1305-0606-4202".