Grantoo, which makes a multiplayer tournament platform for mobile games, will now enable mobile app developers to give virtual goods as rewards in tournaments.

Developers can use Grantoo to add multiplayer tournaments to their games. Players can send each other challenges to beat a high score, and Grantoo makes that happen and records who won the match. That makes the games more social, more engaging, and more likely to spread in a viral fashion. In turn, it increases the chance that the game will generate revenues for the developer.

In the past three months, Grantoo’s registered user base has grown from 1 million to 10 million. Grantoo is now updating its PropellerSDK so that developers can award virtual goods as prizes in tournaments. That helps them increase the lifetime value of players as virtual goods encourage them to play harder and make the games more exciting. That has been proven in non-Grantoo games like League of Legends and Marvel: Avengers Alliance.

Among the developers using Grantoo is Spry Fox, the creator of the hit game Triple Town.

“Triple Town players seem to really enjoy Grantoo tournaments, and we’ve found the Grantoo team to be exceptionally responsive to our needs,” said David Edery, the CEO of Spry Fox. “It’s been a great integration experience thus far.”

Triple Town uses the PropellerSDK to enable its Boom Town mode, where players compete head-to-head to reach the highest score in two minutes. The winner gets extra points added to his tournament standing. Mikhael Naayem, the founder of Grantoo, said that in games like Triple Town, PropellerSDK’s usage rate can be as high as 30 percent of active players per day. Grantoo players play three times longer on average than non-Grantoo players, and 68 percent are more likely to make an in-app purchase.

The SDK can be modified so that it looks like a part of the existing game. Grantoo, which has offices in Vancouver and San Francisco, also embeds ads in its tournaments. And those ads are much more effective than banner ads at getting users to click through.

Grantoo was founded in 2011 by Dimitri Sillam and Naayem. It has raised $3 million to date and has 10 employees. For sponsored charity tournaments, 100 percent of Grantoo tournament prizes go to the cause or student of the winners’ choice, so the donations are completely tax-deductible.

For companies that want to sponsor regular games (no tuition prizes) and advertising, the money goes to Grantoo, the for-profit company.