If the latest rumours are correct, Apple will formally unveil the European iPhone next Tuesday, and announce which operator has bagged the exclusive rights to sell it here in the UK.

The iPhone's tactile touchscreen interface is one of its big selling points, but there are plenty of similarly endowed rivals hitting the market, too. Take Sony Ericsson's W950i, Samsung's upcoming P520, or LG's Prada phone, to name just three. And let's not forget Nokia has announced that it'll be releasing touchscreen handsets next year.

From a pocket gamer perspective, all this raises some questions: What does it mean for mobile gaming? Will developers be taking advantage of these new touchscreen phones, and if so, how will it affect the gameplay?

Of course, there's one current, very clear example of how a touchscreen can change gaming. "Nintendo DS has already shown lots of great ideas about what's possible with touchscreen," says Mr Goodliving's Markus Pasula.

He's not alone in having observed this, obviously. "Pocket-sized touchscreen devices are full of possibilities waiting to be tapped," adds Universomo's Markku Hakala. "As proven by many DS and Palm [PDA] games, touchscreen works brilliantly, from simple casual games to hardcore RTS games. Combined with even bigger phone screen displays, increased processing power and hardware-accelerated graphics, this brings mobile closer to other handheld platforms, making it a more credible platform among core gamers as well."

Hopefully touchscreen games won't just be a new way to copy what Nintendo's done with DS, though. John Chasey, of developer Finblade, is confident the two platforms won't be the same. "There are some major differences between a DS and touchscreen mobile that shouldn't be discounted," he begins.

"First, watching my daughter bashing the DS excitedly, playing WarioWare, I doubt I'll let her in range of an iPhone anytime soon for fear of it requiring a warranty return. Also, when you have two screens and a stylus versus those thick fingers getting in the way of what's happening on the touchscreen, you start getting some interesting design contraints."

The right game
Naturally, not all games are likely to be suited to this type of player input. Indeed, Pasula suggests that touchscreen controls work really well with casual puzzle games ported from PC (one of RealArcade, Mr Goodliving's parent company, specialities). I-play's Chris Wright is in agreement, pointing out that some of his company's games like Jewel Quest and Slingo Quest would be ideal for touchscreen input.

Jim Blackhurst at Eidos, meanwhile, thinks it's important to realise other genres are likely to benefit. "Touchscreens work well with casual games, where the mechanic is sorting or positioning," he says. "Our own game, Prism: Light The Way, is a perfect example of how a touchscreen interface lifts the challenge away from the control system and places it back in the gameplay where it's supposed to be."

Blackhurst also suggests that as touchscreen handsets become more common, we'll see new genres popularised on mobile, including RTS games, and the 'point-and-click' genre of PC games (think the Mystery Case Files series, for example).

"Mobile games developers have been waiting for analogue input for too long," he says. "Touchscreens aren't the perfect input device, but they are a billion times better for most games than the phone's number buttons."

Potential issues
What about the downside of touchscreen gaming, though? One challenge is that not all game genres suit touchscreen input, which could become a problem for future phones that don't have a physical keypad. Blackhurst counters with the fact that DS has proved most genres can be adapted – but then, DS has a D-pad and physical buttons alongside its touchscreen.

"The ideal would be to have both the keypad four-way control system, and a touchscreen display so you can get the digital interactivity needed for action games, and the ability to create unique touchscreen interaction where it makes sense," offers Chris Wright.

One obvious way of looking at this is to admit some genres simply don't work on a touchscreen-only interface – take beat-'em-ups, for example. However, another approach would be to hope that this becomes an incentive for developers to come up with new control methods for those tricky genres that do work. Street Fighter Touch? It could happen. Honest.

But the largest barrier likely to hold back the number of touchscreen mobile games is the hassle of porting the titles across. "The biggest challenge lies in the fact that, for market reasons, most games have to work on both keypad-only and touchscreen-only handsets," says Hakala. "For some games, this is a no-brainer, but for others this means big challenges in game design. Pac-Man is simply not the same without a joystick."

The iPhone problem
In short, for now developers and publishers have to weigh up the value of producing a separate touchscreen version of a game that'll add more development costs, yet only be available on a few phones.

For something like the iPhone, which has already sold a million units, this expense is worthwhile, but here too there may be challenges, not least the fact that iPhone is a closed environment so, as Chasey points out: "Games will happen with the blessing of Apple or not at all".

And he goes on to suggest that iPhone will bring its own development restrictions. "If you thought Sony or Microsoft were anal about user interface standards on their consoles, Apple take it to a whole new level," he says.

"Having spoken to some of the developers that worked on iPod titles, there are some very strict rules that are imposed and there is no reason to believe these will not be applied to the iPhone also. The restrictions on how input is handled is not because the hardware is limited, but because that's how Apple want the interface to behave, no matter that it's not necessarily the best approach for a particular game."

This could work in one of two ways: either it'll be a positive approach in terms of standardising touchscreen game interfaces across the iPhone, or it'll end up restricting developers.

The future's bright?
However, for other touchscreen phones that haven't yet got iPhone-esque sales figures, the issue is a more immediate one – it's too early for developers to start splashing the cash on creating bespoke games for them.

"When you are having to support 500 handsets, during porting the focus ends up being on getting the title to work and run on those phones," says Chasey. "Totally revamping the UI [user interface] for the sake of a couple of touchscreen handsets tends to be fairly low on the priority list for most publishers."

Having said that, developers are certainly interested in the potential for touchscreens, but are waiting to see if it becomes financially worthwhile to support them.

"Overall I would say the benefits for the game community outweigh the costs," believes Hakala. "Maybe at some point the market will even change, so the same game doesn't have to be fitted to all the handsets, from the very low-end to the super high-end. Or maybe that's just another daydream!"

Ultimately, there's no question of the control revolution touchscreen technology would bring to mobile games. Just as there's little doubt most mobile game developers are excited by the prospect of such a move.

But the reality is that mobile gamers shouldn't ditch their keypad-bound handsets in favour of their touchscreen-enabled cousins just yet, warns John Chasey. "It's got great potential, but the jury is still out on whether it will be delivered."