When Maximo Cavazzani, creator of the popular mobile game Trivia Crack, learned about Apple Inc's plan for a new smart watch, it seemed like a logical step to adapt his game for the new product. But the little watch had some big limitations.
The tiny screen and compact processor required simpler animation, which meant scaling back the game's trademark trivia wheel. And some things, such as pop-up ads that help make phone apps profitable, weren't possible when designing for the watch.
Designers, including Cavazzani, are generally optimistic about the possibilities of the new watch, the first product developed under Chief Executive Tim Cook, but many are finding that designing for tiny screens requires a new approach.
Just as the development of apps has been crucial to the success of Apple's iPads and iPhones, the Apple Watch's popularity, and ultimately its sales, will depend in large part upon the apps outside developers come up with to expand its usefulness.
"You can do some cool stuff, but of course it has limitations," Cavazzani said, and making money "is a little bit complicated if it's not a paid app - there's no way of putting ads and no way to do in-app purchases."
Apple has touted health and fitness tracking, communication and style as the chief reasons to buy its wearable, but games are some of the most lucrative apps on the iPhone.
Of the more than 5,600 apps created for the timepiece so far, about 10% are games, compared with 20% of iOS apps overall, according to App Annie, a mobile analytics firm.
Pioneers are looking for ways to promote very short bursts of play. Some games keep progressing without the wearer, for instance.
"Most people are super sceptical," said Tero Kuittinen, a managing director of Frank N. Magid Associates who consults with app developers. "You have to rethink every assumption you have" about keeping players engaged.
Apple is planning more flexibility, as well. At its Worldwide Developers Conference in San Francisco next week it will show off a bigger tool kit for developers to help create apps that capitalise on the watch's array of components.
Jeff Williams, Apple's senior vice president of operations, said at a recent conference that the first batch of apps built with the new tools will likely arrive in the fall. Developers say they expect to be able to create apps that are quicker and richer with the new tools.
Other changes may also come. The Watch is not technically incapable of carrying ads, for instance, but many major ad networks do not support the watch yet.
Major players are trying Apple Watch: game titan Electronic Arts is developing apps for two popular games for the time piece, Real Racing 3 and FIFA 15 Ultimate Team.
"It turns out you can do a lot of fun things on a small screen," said Matt Bromberg, an executive at Electronic Arts. Rival game maker Zynga has yet to release any Apple Watch apps, though. It declined to comment.
Most developers agree simplicity is a virtue for games to be played on gadgets with screen sizes measuring 38 or 42 millimetres.
The developers of Runeblade, a fantasy game developed for the watch, achieved that by freeing users up from the job of actually playing the game: Players make key decisions in a war against corrupt gods and monsters, and then the game keeps running as they move on to other tasks. The game challenges players to stop ancient gods who have returned to wreak havoc.
In the time it takes to wait out a red light, players can cast spells to propel them forward in the game. Though players typically drop into the fantasy world for just five to 15 seconds, some are returning as much as 100 times a day, said Aki Järvilehto, CEO of Everywear Games, the Finnish studio behind Runeblade.
The Apple Watch is always "a glance away," he said. "We are thinking it's the game platform of 2015."