It's that model that's behind Battlefield Heroes, EA's rethink of its best-selling team shooter series as a browser-based, casual gamer friendly cartoonish war. It'll be free to create an account and play whenever you want, but that way your character will look pretty bland and have only basic abilities. To change that, you pay. "Maybe you want the gold helmet and a huge moustache, or something like that", suggests DICE's developer Ben Cousins.

Alternatively, you can improve your character: "Let's imagine that the two of us are playing the game, and you're playing the game every night for four hours, you're levelling up your guy really fast, but I only play the game a couple of evenings a week. So maybe I'll buy an item which gives me double the experience points for a couple of days."

The trick is finding a balance between something that makes the folk who pay for it feel sufficiently special and also ensuring the folk who don't want to pay don't feel like they're on a back foot. They may not be paying, but there absolutely has to be a big, happy, word-spreading community in order to attract new players who might pay.

Sony's attempting a similar thing with upcoming MMO Free Realms, currently in closed beta. It's a colourful fantasy world aimed at children and casual gamers – while it might have the levelling and stat-boosting of something like World of Warcraft, it largely constitutes a series of mini-games, such as fighting, racing and match-3 puzzles.

It's a massive playground full of distractions, essentially, and its high polish, high customisation appearance could pull in a huge crowd. To fund itself, it's trying every trick in the book – adverts on loading screens, free bonus items sponsored by brands such as Best Buy, a paid subscription to unlock extra content, a real-world collectable card game and comic and, of course, micropayment items, notably character customisation stuff like haircuts, clothing and pets.

Is add-on content the only way forward?

Sony promise the free game will be high-quality and full-featured, but the sheer number of ways it'll be prompting people (kids, specifically) to spend money brings up a fundamental concern about free gaming in general.

Do free games have to noticeably badger its players to buy extra content in order to survive and, if so, at what point do they become annoyed or uncomfortable about it? On the other side of the coin is Quake Live, id Software's free, browser-based relaunch of its classic multiplayer shooter Quake III.

For now, it has in-game billboards and that's it. That's the sort of thing you see in paid games, so it's hard to balk at them. There are more plans in the offing, reportedly – paid-for character models and your favourite level maps from days gone by are the most likely bets. The question there is at what point a player thinks, "well, I can buy Quake III for a fiver and then download the other bits for free".

This is a very young form of gaming, and no doubt we're in for several years of trial and error before the perfect balance is found. Until then, traditional paid games aren't going anywhere - there's still something to be said for knowing your £30 buys you a complete experience. Then again, we're increasingly seeing 360 and PS3 games offering additional, and often very desirable, content for a few quid - so getting the initial game for free, even if it's a barebones experience, starts looking appealing again after all.

One additional hurdle for free gaming is the name, and the negative connotations thereof. "Our hope - and the basket we're putting our eggs in - is that 'free' will soon be disassociated with 'shallow' and 'cruddy'," says Flashbang's Steve Swink." For Edmund McMillen, 'free' is very much a positive concept:

"True creative freedom is the biggest appeal about doing freeware games. When you step into console dev, no matter how much you want to think you're totally indie, you're not. You're still at the whim of your publisher, they have the final say and if they don't like something you're going to have to change it to get it published."

So even if publishers turn free gaming into a distasteful minefield of paid bonus content and advertising barrages, there'll still be developers embracing the absolute freedom it offers. Free gaming, one way or another, is here to stay.

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