When it comes to mobile games companies with experience of micro-transactions, no one is better informed than Korean publishers such as Com2uS.

It's been running the sale of virtual items in its free and paid games for years now.

We caught up with Joony Koo, Com2uS' team leader for global business development team, to get some idea of how the system has been working, and how the company plans to take that knowledge onto the App Store.

Pocket Gamer: What's Com2uS' experience with micro-transactions in mobile games?

Joony Koo: In Korea, Com2uS has been servicing in-app or micro transaction services in mobile games for about four years now. In some role-playing games, the average revenue per user (ARPU) is as much as 100 percent of the initial game price: the game price typically being 3,000-4,000 wons ($3-$4).

More generally though, the average additional revenue per micro-transactional game is about 30-40 percent. And even if it's a free game, the average revenue generated will be $1-$2.

However, not all users are prepared to pay for micro transactions. We've found around 30 percent are willing to pay for such extras.

Another thing about in-app items is they can have a big effect on the balance of the game. If a game relies too much on in-app items, the 70 percent of players who won't buy in-app items will stop playing.

We've also found users tend to spend more on in-app purchases if they've paid for the game compared to for a free game. Obviously, users have more devotion for a game they've paid for than for something free.

How significant do you think the addition of in-app payments for free apps is in terms of stopping iPhone app piracy?

I don't think it will make much difference to be honest. Free games with in-app purchases will be free from piracy. After all, why would anyone get a pirated version of a game when the original is free?

When it comes to paid games, I don't think there will be much difference. People who are used to getting pirated versions of games will continue to get them.

How do you think this will change the Free, Paid and Top Grossing charts?

We're thinking of asking Apple actually! We'll let you know if there's a straightforward answer. But if not - which is more likely - there'll be assumptions and wild guesses.

For example, how many people know exactly how the App Store ranking system works now, apart for the fact it's based on download numbers (Free/Paid) and revenue (Top Grossing)?

Do you plan to release free micro-transaction supported games?

Yes. We have a game that will work well with the free micro-transaction support. It's an MMORPG and it will go live early in 2010.

Homerun Battle 3D, which is a paid game, will also include in-app items in the next 1.3.0 update.

Thanks to Joony for his time.

You can keep up to date with Com2uS via web, Facebook and Twitter.