At first glance, HTML5 seems to offer some huge advantages for online and mobile game developers. As a purely web-based platform, game makers can create their game in HTML5, and release it on any number of supported devices, from phones to PCs and beyond. But is it really as easy as it sounds?

The platform doesn't have a final specification yet, so its capabilities are very much in flux. It's shown clear signs of promise, and major developers like Zynga have already begun supporting it for their mobile releases, but companies such as on engine provider Unity claim HTML5 "isn't where it should be in terms of performance."

With no clear consensus on where the platform is headed, we've decided to talk to some of the developers most involved with HTML5 to get their perspective, diving into the platform's greatest strengths, it shortcomings, and where it might be headed in the future.

The following is a list of the most important things to know about the current state of HTML5:

1. It's Designed To Work Cross-Platform

HTML5's primary advantage is that it works across a wide range of devices, from PC browsers to mobile phones, tablets, and even Smart TVs. As long as a device uses a browser equipped to run HTML5, it can theoretically serve as a viable platform for HTML5 games.

This offers a huge advantage over native apps, which often have to be completely redesigned for their target operating system. If a developer wants to bring his or her iOS title to Android, for instance, they'll have to make some fundamental changes to their game. With HTML5, that process should be a bit easier.

"We've supported the drive to HTML5 for over a year now, and we see great value in the ability to outfit browser-based games for any device. This is becoming more and more important as gamers play more often and on multiple devices," said Peter Driessen, CEO of major web game publisher Spil Games.

"We think there are a few reasons to go with HTML5," said Zynga Germany's Paul Bakaus, who helps build tech for the company's numerous web and mobile games.

"One benefit is the ability to distribute it easily on mobile web browsers. You don't have to install it, for instance -- that's one significant advantage. There's also the thing with content updating and cross-platform development. If you're building a native app, it's likely that you have to build your app twice on Android and iOS, and on desktop maybe, too. On HTML5, you build your app once, and you can port it to multiple different devices," he said.

In addition to allowing developers to more easily put their games on multiple platforms, HTML5 also allows for easy cross-platform communication, allowing for a host of cloud-based features, ranging from social systems to persistent game worlds.

"What we're ultimately looking to accomplish through HTML5 is true cloud gaming. We support a large online community and it's been obvious that our players, much like gamers everywhere, are increasingly looking to play games on their mobile phones. HTML5 sets the foundation for us to create a seamless experience, which includes social functions, on browsers both on the go and at home," explained Spil's Driessen.

2. HTML5 Offers Unpredictable Performance

While HTML5 might be designed to run on a wide range of devices, there's still no reliable way to maintain performance across varying hardware specifications.

EA creative director Richard Hilleman recently shared his frustrations with the platform at the San Francisco-based New Game Conference, noting that his team's experimental 3D animations ran great on a MacBook Air, but chugged on more powerful hardware.

"On my own computer, which runs on an i7, I couldn't get more than a few frames per second [from our demo]," Hilleman said. He explained that "high performance JavaScript is obtuse at best," so it's hard to predict how an app will run on a given hardware specification.

"I don't know how to explain that to a customer. That's a big, big problem," he added.

Mobile-focused HTML5 developers are particularly susceptible to these problems, as their games need to run on a wide array of smartphones and other mobile devices.

Stewart Putney, an experienced HTML5 developer and former CEO of the recently shuttered Moblyng, told Gamasutra that his company would test its games on literally dozens of devices. "For iOS it is simple: 3GS, 4, 4S, iPad, iPad2. Android is much more fragmented; each handset manufacturer tends to make small -- mostly undocumented -- changes to the browser on their devices. For native Android apps, this is no big deal. For HTML5 apps, it can mean apps simply don't work," he said.

"To get good quality, our apps must be tested on a range of popular devices -- it is the only way to be sure apps are working properly. I believe we will see more testing tools and better standards moving forward -- but Android QA is a real pain point for HTML5 development," he continued.

3. It's An Alternative To Flash

Traditionally, Flash and web games have gone hand in hand, but with Adobe's recent decision to cease development of Flash for mobile browsers, developers will have to look at alternatives for the smartphone market. But how does HTML5 compare?

According to Zynga's Paul Bakaus, there's still a place for both, as they each offer their own unique specialties.

"Well, Flash has this new Stage 3D API, while the web has WebGL. Both of them are using native OpenGL calls on the bottom layer, so they're comparable in speed," he explained. "Now, regarding software drawing, I think HTML5 has actually surpassed Flash because it's so close to the actual browser, so they can drive various optimizations on a hardware accelerated layer. But Flash has some very significant advantages too."

"I'm seeing great 3D applications come from Flash and Stage 3D, and seeing HTML5 really being the way to go cross-platform. And then there are native apps too, which are a great way to integrate with the OS on mobile phones. I'm not sure if there's ever going to be a winner -- I wouldn't separate them so. I think it'll be more like specializations."

Google's Seth Ladd added that he expects HTML5 to eventually coexist with Flash, with each platform offering its own unique benefits.

"I think that what you'll see is that all of the different platforms that make up the greater web as we know it will be able to get pushed forward because there is now some competition," he said. "I expect that Flash will find another angle for which they can optimize their experience, and the open web platform will find another way in which they can optimize their experience, and then you can see those play out. And that's really great for end users."

Others, like web developer Dominic Szablewski (creator of the JavaScript-based Impact engine), say Flash might work well for artists and the like, while HTML5 is a great environment for those who like to code.

"Flash was always great for creative people. Creating animations or very simple games is pretty easy with the Flash IDE and a few mouse clicks. Such a tool is still largely absent for HTML5; you really have to write code to do something."

"However, HTML5 is completely free -- to get started, you just need a browser and text editor, no need to purchase an expensive application."

Szablewski added that with Flash no longer an option for mobile, he views HTML5 as the future of web development. As he puts it, "If you want to build stuff that works in mobile browsers, if you don't care about IE6/7/8 users, and if you don't want to use a dying technology, use HTML5."

Regardless of how it compares to Flash, mobile companies looking to go cross-platform might have little choice but to turn to HTML5. At least, so says Moblyng veteran Stewart Putney.

"Since there is no Flash support on Mobile, I'm betting that HTML5 will become the cross-platform standard in mobile. And so far, it looks like that is becoming true."

4. Audio Is a Big Problem

Sound undeniably plays a crucial role in game development, yet unfortunately this is one area where HTML5 really falls short. The APIs available for the platform just pale in comparison to those available for native app development.

Zynga Germany's Paul Bakaus particularly laments this shortcoming. "The number one challenge with HTML5 is audio, and this needs to be fixed. It's as simple as that. There's no way we can work around audio, right? Audio is needed for great games. This is the biggest challenge, but I wouldn't say stop building games because of that."

He explained that he thinks web developers will be able to fix these audio issues, but a few things need to happen before that becomes a possibility.

"There are two things that I think need to drive audio," he said. "One of them is actually us, as I mentioned before. We need to make vendors aware of the problem, so we need to create games, and we need to tell them about the shortcomings our games have."

"On the other hand, we really need vendors to accept that this is a problem, and work against it. I see it less prioritized than fixing graphics right now, and that's a huge concern I'm having. As a vendor, you're not really thinking in the game world, right? You're not realizing that in order to make good games, audio is needed. We really just need to make them aware of the problem," he said.

Electronic Arts creative director Richard Hilleman agrees with Bakaus, as he explained during his keynote at the 2011 New Game Conference. "One thing that didn't go well for us was sound," he said. "We still tend to falter with sound on HTML5, and we have to resolve that... I have some hopes the next iterations of the browser will address that, but it's another big problem."

5. Browser Compatibility Isn't Uniform

If your players are running more recent browsers such as Chrome or Firefox, they should be able to play your HTML5 games just fine. But what about those still using older browsers like Internet Explorer 6, or previous versions of Safari or Opera? If users aren't updating their browsers, they won't have access to all of your HTML5 content.

At times, these browser compatibility issues work against one of the platform's greatest strengths: its ubiquity. If users are still using older browsers, they're excluded from playing HTML5 games.

Some developers, like Zynga's Bakaus, believe the best way to overcome this problem is to simply push forward with development, even when limited to newer browsers. By creating quality games that don't work with older software, users will be incentivized to upgrade, he argues.

"People are scared to abandon users at less than Internet Explorer 9," he said. "But sometimes, giving people what they want isn't helpful, since nothing will change. Try to come up with great new stuff that only works in modern browsers, and that will create incentive to upgrade," he said.

But if all users are running HTML5-enabled browsers, does this mean web apps will run equally well across all of them? Not necessarily.

Even when you look at browsers that support HTML5, that support is not uniform; older HTML5-enabled browsers might support only a limited number of features or APIs, meaning certain game features are only available to those who keep up with the latest browser releases.

And of course, if you're working with a limited budget, you might now have the resources to make a game that works across all browsers. At the New Game Conference in San Francisco, Bocoup's Darius Kazemi recalled that he encountered that very problem when porting Subatomic Studios' Fieldrunners to HTML5.

Kazemi explained that due to time and budget restrictions, he and his team chose to develop the game specifically for Google Chrome and the Chrome Web Store.

"Here's the dilemma," Kazemi said, "Do I reach the widest audience possible, or do I create the highest quality game? Can I have both?"

"In the end, do we get it on other browsers, or do we just create that quality experience on one browser? We ended up doing [the latter]."

Kazemi added that the game benefitted from some of the APIs that shipped with Chrome 14, but in the end the game was bound to a single browser. If you're going for platform ubiquity with your HTML5 games, be careful to plan your resources accordingly.

6. There's No "App Store"

One of the key ways in which HTML5 apps differ from native apps on mobile devices is that they lack a centralized app store to keep everything in line. This comes with its own set of pros and cons, but it's certainly worth noting before diving into the platform.

Of course, the main benefit of working on the web is that there's no approval process to submit, launch, or update your game. Unlike closed platforms like Apple's iTunes Marketplace, HTML5 allows you to update or launch your game whenever you like, with no need to wait through the bureaucracy of a platform holder.

While this freedom might seem appealing to up-and-coming developers, it comes with at a cost. Without a standardized distribution platform, getting your app in front of players becomes much more of a challenge.

"Right now, we do not have a major HTML5 'app store' to aid in discovery," said Putney.

Without a single destination for HTML5 apps, it becomes much more difficult for players to even learn about a new release. Putney said, however, that Facebook could certainly help in this regard.

"With Facebook enabling the social discovery of HTML5 apps on their mobile platform, it is a huge step forward," he said.

Google, on the other hand, views the open nature of HTML5 as one of its greatest strengths. The company's Seth Ladd explained, "I might say that it's actually easier to publish and distribute, because there's no governing body there, there's no up-front approval process. Everyone gets the freedom to monetize the way they want, log in to users the way they want, and publish they way they want. This is one of the strengths of the 'open' part of the open web platform."

7. It's Still Evolving

With all of HTML5's advantages and shortcomings, you'll have to decide for yourself whether it's right for you. Currently, there's no final specification for HTML5, but web developers are constantly adding to the platform, so who knows what things will look like in the coming years.

Google's Seth Ladd has high hopes for the future of HTML5, and notes that with such rapid iteration coming from the various working groups on the web, the platform is evolving faster than ever.

"I think what you're seeing now with Chrome, and Firefox, and even Internet Explorer to an extent, is that the specifications that come out of the different working groups in the spec bodies are moving at a much faster rate than they've ever moved before," he said.

With so many parties actively working on the platform, some HTML5 developers say it will only become more robust as time goes on. HTML5 developer Dominic Szablewski added, "This is HTML5's greatest strength. There's competition. After years and years of IE6 and Flash there's finally some progress with web technologies again and it's only just beginning. There's so much going on right now: WebGL, fullscreen mode, mouse lock, new audio APIs. It's truly exciting."

Companies like Zynga admit that HTML5 still has a long way to go until it can really compete with native app development, but if the platform can maintain its growth, the playing field could eventually even out.

Zynga's Bakaus said, "We're still early and that native apps have focused on game development for a long time already, so they've just had a ramp-up that we haven't yet."

Despite the optimism from existing HTML5 developers, the platform is still a challenge to work with given its ever-evolving state. Putney said, "We are essentially working on a car that is moving," noting that the changing specifications can introduce a number of technical hurdles in mid-development.

"But if we get things right, we can reach hundreds of millions of users with a successful app -- so we believe it is worth it," he said.