Sega Mobile has sold more than 8 million downloads of its Sonic the Hedgehog game since its mobile launch two years ago in North America and Europe.

The mobile game has been one of the consistent bestsellers on Verizon Wireless' V Cast on-deck service, accounting for more than 3 million downloads alone from that carrier. The game continues to sell more than 100,000 units a month across all wireless carriers, according to Sega Mobile.

"It's not only a popular game, it's a classic," said Carrie Cowan, director of marketing at Sega Mobile, San Francisco. "It doesn't get old. It resonates with older audiences who grew up playing the game and newer audiences too. It's really multigenerational."

Sonic has run in more than 40 games on 19 video game platforms. The mobile game was a recreation of the first title for the Sega Genesis console system.

The mobile game was first launched nationwide through Verizon Wireless. It is now available through major carriers in North America and Europe.

Targeted to casual gamers, Sonic is about a ride with the fastest blue hedgehog on earth, taking players through loop-de-loops and dizzying dives past bubbling lava and waterfalls to gather rings and stop the evil Dr. Robotnik's plan for world domination.

The mobile game has one-thumb controls and console-like graphics.

"It's one of the games when we brought it to mobile we didn't do much to change," Ms. Cowan said.

The game costs $7.99 for a one-time download or $3.49 a month for an annual subscription.

Sega Mobile plans to introduce three new Sonic titles this year, including "Sonic at the Olympic Games," "Sonic Spinball" and "Sonic the Hedgehog 2."

"This year is our coming-out year for North America," Ms. Cowan said. "We're bringing some of our best brands to mobile and re-establishing our position as a premier publisher for games on wireless devices."

The Sonic milestone comes at the same time that Sega Mobile hired Tammy Robinson as senior director of sales. Ms. Robinson was manager of content programming for games, wallpaper and applications at Verizon Wireless.

Ms. Robinson is charged with leading Sega Mobile sales and planning efforts related to mobile products and distribution channels. She will also manage channel relationships with carriers and handset makers.

During her 10-year stint at Verizon Wireless, Ms. Robinson was one of the key executives who made mobile games a major category in the carrier's downloadable content catalog.

Mobile is a key component of Sega Mobile's growth plans.

"It's a great platform to reach our casual audience," Ms. Cowan said. "It's becoming an increasingly important audience for every game publisher. Not only that, we're learning a lot about distributing content in a new digital medium."