Selecting a game engine used to be a snap when there was only a handful from which to choose.

But today, developers have a plethora of possibilities -- from rolling their own to licensing an engine originally built for a specific game (like the Unreal Engine) to licensing a generic engine (like Emergent's Gamebryo).

To add to the confusion, says San Francisco-based independent games consultant Mark DeLoura, during the past few months the number of game engines available has suddenly increased from a relative few to something that needs a spreadsheet to keep track of.

Which is why, in February, he sent out a survey to industry executives asking for their feedback on the use of game engines. Last month, he shared some of his results on his Gamasutra blog.

Faced with such a grand buffet of choices, how do successful developers make their selections?

Alex Seropian considers himself "engine agnostic," having had all three experiences -- first, creating the Halo Engine at Bungie, then -- at Wideload -- using the Unreal Engine for a very un-"Unreal"-like Hail To The Chimp, and, finally, employing the Gamebryo Engine for the soon-to-be released Texas Cheat 'Em. Seropian is president and founder of Chicago-based Wideload Games.

But what was there about each project that influenced him to make the decisions that he did?

Choosing to create an engine -- the Halo Engine -- for Halo back in 1991 was a no-brainer, recalls Seropian. "Eighteen years ago you really didn't have many choices," he says. "Besides, the team at Bungie wanted to build Halo around some very particular technology features and core mechanics, and that necessitated our constructing our own game engine."

The project -- building both the engine and the first Halo game -- took almost nine years until the Xbox platform was released in 2001.

"It's a long, long process," says Seropian, "and things have changed since then. Teams are bigger, projects are more expensive, and anyone who, today, wonders 'Hey, should I start up a game project from absolutely nothing and write every piece of code from scratch?' needs to know what a very big, daunting, multi-year investment it is."

Indeed, exactly a year ago, Wideload released Cyclomite, one of its "Shorts" (or casual) games using the Torque Engine which it licensed. But first Wideload prototyped the game by writing its own 2D sprite engine.

"Even that took us four months to build," notes Seropian. "But if we had wanted to write a 3D engine that was going to be competitive on a next-gen console, that would have taken many, many years. To start making an engine today that's going to compete with Halo 3 or Gears of War, that's a four-year investment."

"If you've got a large enough team that's really funded well or if you have a specific feature in mind that you're looking to exploit, then that's practical. For an independent developer like me, that's definitely not practical."

Gamecock/Wideload's Hail to the Chimp

And so, for Wideload's Hail To The Chimp -- a party game comprised of a collection of mini-games -- Seropian looked at five different engines, but turned to the Unreal Engine 3 for several reasons.

"First, we license engines in general because we are a small, 25-person company and we want to stay that way," explains Seropian. "Second, we were building Chimp for both the Xbox 360 and the PlayStation 3, and the Unreal Engine targets both those platforms."

"And the third and most important reason was that the Unreal 3 offered all the systems that we needed -- one for save games, one for networking, one for the interface we were building, and so on. Basically, for us, it was a soup-to-nuts solution."