'Intangible’ is a word that comes up a lot when the first crop of iPhone and iPod Touch games are being discussed, and it’s hard to see that as a good sign.

Despite Apple’s extended hot streak in the digital marketplace, despite the David and Goliath goodwill, despite the instantaneous success of the App Store as a money-making machine, there’s something indistinct and gently underwhelming about a lot of iTunes’ more playful output to date.

IPhone games aren’t bad, many of them just aren’t terribly memorable: you may touch them, shaking, prodding, jabbing and tilting your way through marble runs, trivia quizzes and side-scrolling shooters, but they often fail to have any lasting impact in return.

Ironically, the underlying problem is something it’s hard to put your finger on precisely. That’s not to say iPhone games aren’t selling: conservative estimates suggest App Store revenues run at a million dollars per day. As a single example, Super Monkey Ball took a mere three weeks to shift 300,000 copies – despite featuring controls so poorly calibrated that it’s virtually unplayable.

It looks the part, and perhaps that’s enough for now, but it’s far from the only proof that people are willing to buy games for the platform. But just what are people buying? In among the 1,200 titles available at the time of writing, there are some promising distractions and a handful of quiet gems, but there are also a lot of misguided, buggy or merely bland offerings – unbalanced puzzlers, slippery kart racers and the odd app that won’t even load half the time.

The sales figures and the hype suggest that the world of handheld gaming is in line for a very fashionable makeover, yet so far Apple’s iPhone has struggled to find its own voice. That contradiction, along with the audible mutterings over just how seriously Apple is taking games, suggests some interesting questions about the platform’s future. Why have so many of the initial releases been so disposable? What are the particular challenges iPhone developers face as the platform matures? And where will iPhone eventually fit in the handheld market?

Gary Penn, internal development manager at ‘digital toy’ maker Denki, is just one observer who isn’t yet convinced by iPhone gaming. “The initial iPhone games line-up is rank,” he declares. “There’s nothing I want to play for even a few minutes. It’s as if no one cares about the device or the medium. Everyone’s so busy clambering over each other to make a mark before the paying players calm down and stop buying any old rubbish.”