"Unfair Mario" is an online game that's based on the "Super Mario" series. It includes hidden traps and misleading messages designed to trick the player. The game is available on Unfair-Mario.com, as of July 2015.

In "Unfair Mario," the player controls Mario with the arrow keys. The left and right arrow keys move Mario in those directions, while the up arrow key makes him jump.

Hidden obstacles include ground that sinks when Mario steps on it, spikes that rise from the ground or descend from objects above Mario, and blocks that fall when Mario lands on them. When Mario lands on a trap or falls, he dies. The game tracks the amount of times Mario has died.

Levels have checkpoint flags and ending flags. After a player reaches the checkpoint flag, he restarts from that flag if Mario dies. When he reaches the ending flag, he has completed the level.