The Pony Express is the latest Google Doodle to be featured on the search engines homepage to commemorate the 155th anniversary of the mid-1800s cross-country mail delivery system.

But, what you may not know is the Google Doodle is actually a game you can play.

Before e-mail, people actually wrote letters and counted on the country’s mail delivery system to get their messages to others. Even before the modern U.S. Postal Service used automobiles to deliver the mail, the Pony Express was used in the 1800s to get the mail safely delivered.

“In honor of the 155th anniversary of the Pony Express on Tuesday, Google created an animated Doodle game that commemorates the mail delivery service,” reported Time magazine. “If Googlers click on the Wild West-themed Doodle, they can help a pony deliver mail across America.”

Today's #GoogleDoodle celebrates the mail delivery service we had long before email.http://t.co/JY5lRjQ3Rm pic.twitter.com/9ZyBMfZJ1f

— ABC7 News (@abc7newsBayArea) April 14, 2015

The game is simple and pretty easy to finish, but collecting every single letter on your way may be challenging.

Animator Nate Swinehart explained the history of the Pony Express and offered a behind-the-scenes look at the Doodle process in a video:

According to history.net, the Pony Express began mid-1800s when three men came up with the idea to open up a mail delivery system that reached from the Midwest all the way to California. The three men — William H.Russell, Alexander Majors & William B Waddell — designed a system of over one hundred stations, with each station approximately 240 miles long, across the country.

Today marks the 155th Anniversary of the Pony Express mail service, which inspired the Pony Express roller coaster. pic.twitter.com/GjlUFDj2ld

— Knott's Berry Farm (@knotts) April 14, 2015

“The Pony Express employed about eighty deliverymen and had around four hundred to five hundred horses to carry these riders from one post to the next,” says the site. “Monthly pay for these riders was fifty dollars, which were good wages at the time. Although this method of carrying mail was dangerous and difficult, all save one delivery made it to their destination.”

So how did you do on the Google Doodle Pony Express game?