Google+ may represent the biggest threat Facebook has ever faced since it launched more than half a decade ago. But is Google’s new social network, which may be off to the fastest start ever for a social network, already buckling underneath the surface?

Despite the fact that Google may have finally built a social network capable of competing in the market, cracks are showing which raise doubts about Google+’s future prospects.

Crack #1: Google is already kicking users off of Google+.

For obvious reasons, Google doesn’t want ‘fake‘ users infiltrating Google+. After all, there’s a strong argument to be made that Facebook’s early restrictions, which required a .edu email address, helped it acquire an audience of superior quality early on.

But in trying to weed out fake accounts, Google sparked some ire this weekend, as real users were booted from the service. According to Robert Scoble, Vic Gundotra, Google’s social chief, “says [the Google+ team] made some mistakes while doing the first pass at this and they are learning. He also says the team will change how they communicate with people. IE, let them know what they are doing wrong, etc.

That’s obviously a good thing, but the fact that Google is already having to make “tough choices” raises questions about just how much Google can massage (or micromanage) Google+’s evolution before it makes one or more high-stakes missteps.

Crack #2: The spammers are already flocking.

It isn’t necessarily surprising that spammers are already targeting Google+, and more specifically its +1 button. But that doesn’t mean that this shouldn’t be of concern to Google. This type of activity can be very difficult.

Twitter, for instance, has been around for years and the spam keeps coming. That hasn’t killed Twitter, of course, but there are some (myself included) who use it far less because of the spam.

The biggest risk for Google is that spammers will focus even more of their attention on its burgeoning social network in the hopes that Google+ metrics will become ranking signals for Social Search.

Crack #3: Google is preparing to launch a social gaming platform.

Google+ isn’t Facebook, yet that apparently isn’t stopping Google from trying to hit Facebook where it could hurt most. According to reports, Google is planning to launch a platform that would lure social game developers to Google+ with a lower tax than Facebook is requiring developers to pay to use its Credits system, which is now mandatory. Google is already reaching out to developers according to some of the reports.

Of course, that Google+ would eventually support social games seems like a no-brainer, but now is not the time. Google+ is off to a strong start, but Google is nowhere near ready to turn Google+ into a Facebook replacement.

Instead of trying to do everything under the sun as quickly as possible, Google should focus on making Google+ a great social network before it tries to make it a great platform. If it doesn’t, don’t be surprised if Google+ collapses under its own weight as too much is added, too soon.