​In the world of video games, few achievements are as satisfying as unlocking a secret character. However, some of these challenges are so complicated that only the most dedicated players manage to overcome them. Here are three examples that made history:

Reptile in Mortal Kombat (1992)
This green ninja was the first secret character in the series and only appeared under specific conditions. You had to fight in the Pit stage, with a specific planetary alignment in the sky, and win two perfect rounds with a Fatality. All of this, with no in-game hints!

Tofu in Resident Evil 2 (1998)
A playable block of tofu, yes, you read that right. To unlock it, you had to complete the Hunk mode and surpass several challenges in record time. Only the most hardcore fans could face zombies while literally being food.

Luigi in Super Mario Galaxy (2007)
Although it's not as secret today, unlocking Luigi required completing the entire game 100% with Mario. A true challenge for those who wanted to see the universe from a slightly different perspective.​