I'm planning on including a kind of puzzle in my game, but it doesn't use items or variables. Basically, you go around an empty (or so you think) school, and in some of the rooms are things written on chalkboards pertaining to certain colors matching up to certain numbers. Then, later, you find a chalkboard with 3-5 colors in a specific order, which corrospond to a numberpad that must be unlocked to get into the psychiatrist's office. Only then can you continue the game.
What I was thinking of doing is something as simple as possible. Basically, you input the numbers in the correct order or something bad happens. Would it make more sense to have it simply reset the number sequence and make you start over again (potentially giving the player the ability to cheat through trial and error), or have it be a game ending mistake, forcing the player to find and memorize the solution else they lose?
My other question is, what other sort of simple puzzles would be good to use? Preferably ones for use in a classic CYS, without items or variables. Any ideas would be appreciated.