NEW YORK (CNN/Money) - You're going to be hearing a lot about "The Sims Online" over the next week.

Set to launch Dec. 17, the next incarnation of Electronic Arts (ERTS: Research, Estimates) juggernaut PC gaming franchise is widely seen as a litmus test for online gaming. After all, "The Sims" has sold approximately 8 million copies, while its add-ons have sold more than 13 million. The franchise has earned EA more than $800 million and become the best selling game of all time in the process. If the company can convince just 15 percent of those buyers to sign up for the online game (and its monthly $10 fee), it will elevate pay-to-play online gaming from a niche market to a solid industry.

"The Sims Online" is expected to be a sales juggernaut

While there are plenty of pay-to-play online games, the most successful ones are full of swords, sorcery and elves. That may appeal to hard-core gamers, but it does nothing to attract the vastly larger casual audience. "The Sims Online," with initial shipments of 300,000 to 400,000, hopes to change that.

Viewing "The Sims" as the potential hero of the online world is understandable, but there are at least three other franchises on the market that could draw in a mass audience.

Grand Theft Auto: "Grand Theft Auto III" sold more than 4 million copies in 11 months on the PlayStation 2. "Grand Theft Auto: Vice City" sold more than half a million copies the day it was released. If "The Sims" is the beacon of hope for PC pay-to-play gaming, "GTA" is the best thing that could happen for the console world.

Imagine an expansive metropolis, where players can elect to run errands for the mob, drive an ambulance or taxi, maybe even take the role of police officer and apprehend other players on a wilding streak. "GTA" is often singled out for its violence, but the game's real hallmark is its open-ended gameplay. There doesn't have to be a conclusion – and that's key to a persistent online world.

Asked if an online game is in the works, a Rockstar Games spokesman said "that's something we will say when the time is right."

Let's take that as a 'probably.' Sony lets developers decide whether online play is offered free or on a pay-to-play basis. Rockstar (a division of Take Two Interactive Software (TTWO: Research, Estimates)) could go either way, but by slapping a $10 monthly fee on the game, it would see an inflow of cash that few games could approach.

Not everyone agrees. P.J. McNealy, research director at GartnerG2, expects the GTA line will offer additional missions and downloads, rather than an organized online community.

Halo: Microsoft confirms "Halo 2" (due in late 2003) will have a multiplayer element. It hasn't said, though, whether the game will carry an additional monthly fee. My guess is no. By the time "Halo 2" hits shelves, Xbox Live will already be charging members $10 per month or so and the second installment of the Xbox's most popular franchise will be a good incentive for subscribers to pay that fee. Microsoft (MSFT: Research, Estimates) wins either way, however, as it's developing the game internally, meaning it doesn't have to share the sales or online income with anyone.

"Halo 2" should drive substantial traffic to Xbox Live

Developer Bungie Software (a Microsoft studio) won't say too much about what they have in mind for the game, but in an earlier statement, lead designer Jesse Griesemer said "imagine the essential 'Halo' single-player experience: pitched battles between the humans and the Covenant, massive vehicle and infantry engagements. Now imagine that every combatant is an actual person."

WWE: While World Wrestling Entertainment's TV ratings have been slipping for the past year or so, video game sales have remained steady. "Smackdown" and "Raw" have a substantial customer base in the console world, but there has never been the opportunity for players to pit their skills against others outside of the living room.

That should change in late 2003 or early 2004. A THQ (THQI: Research, Estimates) representative tells me that the company is working on at least one online enabled WWE game. It's too early for the company to decide whether to make these pay-to-play or not, but like "Halo," I suspect it won't be. Not charging a monthly fee might expand the player base, but it would also bypass a significant cash inflow.

Punch the orc for previous columns.

It wouldn't take much to make a monthly fee worth it to devoted wrestling fans. Many of the WWE's wrestlers are avid gamers. Regular tournaments pitting the pros against the fans would encourage subscriptions. It's also easy to imagine an online Wrestlemania coinciding with the company's annual Pay Per View, where elite gamers compete for cash and prizes.

Just as "The Sims Online" offers a distinct alternative to today's pay-to-play titles, each of these examples offers a vastly varied style of gameplay. While launching a pay-to-play enterprise carries plenty of risk, the potential reward for these mega-franchises could be tens of millions of dollars.  

Morris is Director of Content Development for CNN/Money. Click here to send him an email.