"Spore" has landed, and the long-awaited video game brings with it an evolutionary shift in how players interact with — and help create — games.

The title, in development for more than four years with "The Sims" creator Will Wright at the helm, breaks new ground in several ways. For starters, "Spore" (out for Windows and Macintosh computers) takes the "god game" genre to extremes with players guiding single-cell organisms through the entire evolutionary process from land creatures to galactic explorers.

Another "Spore" game-changer: Everything players create is transmitted to the game's network, run by publisher Electronic Arts and becomes part of a constantly updated universe. All players will encounter material designed by others, from a menagerie of creatures to buildings and vehicles, in the spirit of sharing that has gained millions of devotees for sites such as YouTube and Facebook.

"A lot of what we had modeled in terms of the social features of 'Spore' was based on social networks," Wright says. "You are creating stuff as you play the game and, with that, basically everybody becomes a creator."

User-generated content has been a part of online computer gaming long before YouTube. Back in the '70s, homegrown text-based multiuser dungeon, or MUD, games began cropping up on networks. And games such as "Doom," "Quake" and "Half-Life" came with tools to create modifications ("mods") and new levels.

But "Spore" makes user-generated content almost automatic. "You are sort of creating without even knowing you are doing it," says PC Gamer magazine's Kristen Salvatore. "With a few rare exceptions, (user-generated content) has been used only among the hard-core community. It has not been that easy (or) accessible for casual or mainstream gamers."

And that seamlessness keeps the quality high, Salvatore says.

"Spore" may be leading the way, but other titles are catching on:

In EA Sports' "Tiger Woods PGA Tour 09" (out now, Xbox 360, Wii and PlayStation 3), players can post videos of remarkable shots and issue challenges (long drives and closest-to-the-pin shots) that will show up in other players' games. Posting and vanquishing challenges earn points.

"Rock Band 2," released Sept. 14 for Xbox 360 (later this fall for Wii and PS3), lets bands issue online challenges worldwide, and an online store allows players to purchase 3-D figurines and T-shirts starring the characters and band logos they have created. And "Guitar Hero World Tour" (out Oct. 26) includes a music studio that players can use to create instrumental tracks that can be shared online.

The next major game to feature user-generated content, "LittleBigPlanet," out next month for PS3, has extensive character customization and lets players create "stages" that other players can download to explore.

"Things like YouTube and Facebook we could see were becoming really popular, and it was trying to apply some of that essence to games," says Mark Healey, co-founder of "LittleBigPlanet" developer Media Molecule.

As video-game development costs rise — "Spore" is estimated at more than $50 million — publishers need ways to recoup investments. Used properly, user content "can extend the life of the purchase and the product you have worked on," Salvatore says.