What was Google's first April Fools' Day hoax, launched in 2000?

Google’s first April Fools’ Day hoax, launched in 2000, was MentalPlex.

The MentalPlex prank claimed Google could determine what users wanted to search for by reading their minds. Visitors were instructed to stare at an animated swirling graphic, concentrate on the desired search, and click to submit the imagined query.

Instead of useful results, the page returned deliberately absurd error messages. One warned of weak or absent mental signals, another complained about analog brainwaves, and others blamed aluminum foil, unclear thoughts, or insufficient conviction. The joke parodied both futuristic mind-reading and the technical language of computer errors.

MentalPlex is often confused with later Google jokes such as Google Gulp, Gmail Motion, and Virgle. Those came in later years: Google Gulp appeared in 2005, Virgle in 2008, and Gmail Motion in 2011. Gmail itself was announced in 2004, but it was a real product despite its April Fools’ timing.