Wario's Whack Attack
From the Super Mario Wiki
Wario's Whack Attack was a browser game that was available to play on Mario Party's official website. Along with Mario's Memory Madness, it is among the oldest Mario-related promotional games released by Nintendo. Wario's Whack Attack was built in Adobe Director and used the Adobe Shockwave 7.0 plug-in.
The player has to help Wario resolve a Piranha Plant infestation caused by Bowser. The gameplay resembles a generic whack-a-mole game where, using the mouse, the player has to hit Piranha Plants as they pop out of the nine pipes on the screen. The goal is to advance through as many rounds as possible by hitting a certain amount of Piranha Plants per round within a time limit. For a round to finish, the player has to wait until the timer reaches 0. Failing to meet the goal in a round results in a game over.
For every Piranha Plant that gets hit, two coins are added to a score. Along with Piranha Plants, multiple Bowser's heads also repeatedly pop out of pipes and have to be avoided. Hitting one of Bowser's heads forces the player to restart the round, and hitting three of them results in a game over. Bowser's heads interfere more frequently as rounds pass.
In the game's introduction, Wario informs the player about the following, via a speech balloon: