This week has seen two big stories about premium games trying to squeeze ever-more money out of their players. They're not immediately obvious bedfellows; Square Enix's Final Fantasy: All the Bravest is a mobile title divided into cash-hungry chunks, and Dead Space 3 is as typical an AAA console title as you'll get. But both excite the same feeling of unease, and not just because they share a common theme of exploitation; it's that point where something bearable becomes too much.

This is nothing to do with the free-to-play business model, but rather the application of its mechanics. Surely everyone loves free-to-play games by now, and the many shining examples across mobile and PC show it can be the basis for top-notch titles. But there are things we acknowledge as players about free-to-play, a familiarity with its structure that means certain mechanics are accepted as inevitable: plenty of cosmetic in-app purchases, a grind-heavy levelling or crafting system, even large sections of the gameworld hived-off without payment. These things, when they are the toll booths for a great free experience, do not bother me.

The thought of paying a tax does hang loosely over my idea of free-to-play mechanics, and perhaps that's why it's so startling to see them in full price games. In terms of Final Fantasy: All the Bravest the up-front cost is £2.49 but, like it or lump it, on the App Store that's a premium. Square Enix has previously released its games (usually ports) at a much higher price, and it's clear this original title is some kind of exploration of how they can reduce the entry point but still get the full whack by the end - it's a game they want £30 for, in other words, so they've chopped it into paid chunks and sold you the first one for £2.49.

FF: ATB has three 'extra' worlds for £2.49 each, plus 35 FF characters at 69p each, a total of just over £30 if you want everything (for which there is an achievement). The hourglasses are 3 for 69p, up to 20 for £1.99.

Now, that's the prerogative of Square Enix. There's another side to FF: ATB which goes even further, however, and strikes me as wholly unethical design. A brief explanation of how the game works; it's a visual reduction of the old-style Final Fantasy 'active time battle' system with a simple touch interface. This is an automated lightshow, where you swipe your finger up and down the ranks of characters, watch them whack away, and occasionally get whacked back. The thing is, it's not all that much of a game; battles are about luck and grind. It's like playing pachinko.

Bad enough, but it's what ties into this that goes beyond reason. This £2.49 game is dependent on a free-to-play time mechanic during game overs - if all of the party in FF: ATB die, you have the choice to restart the battle (pointless, because winning is a matter of time), wait three minutes for each individual character to resurrect (which can take hours), or use one of the hourglass IAPs to revive the party. Let me make this absolutely clear: progression in this game is impossible without either waiting for long periods or paying for hourglasses. It quite simply locks you out.

This is the most cynical and unethical creep of free-to-play mechanics into a paid-for game I've ever seen. I would absolutely love to hear what Square Enix call it. If a company like this is prepared to timelock its players out of premium games then others will follow - and if so, shouldn't that be clearly marked, as distinct from other in-app purchases? Timelocks like this surely have to be addressed by vendors. I cannot fathom why any publisher would think conning people like this is a good idea, yet here we are.

Still, at least players on mobile are much more used to the way these tactics work, and wising up to the cash grabs. The intrusion of microtransactions feels more natural in this space, and many games handle them with considerably more nuance than Square Enix's offering. When you're paying £40 for a game like Dead Space 3, however, where do you draw the line?

Hey Carver, where'd ya get that sweet red helmet? Picked it up at one of those new vending machines greenhorn, some other sucker takes the tab and I get the sugar.

Let's get a few things out of the way: post-launch DLC is fine, cosmetic stuff like costumes is fine, and lots of AAA games offer great value for extra money. The issue with Dead Space 3 is nothing to do with downloadable extras, but the intrusion of a free-to-play mechanic into its high-priced world; you can pay to get extra resources for its weapon-crafting system.

That is not a small part of the experience. I may have a soft spot for Resi, but Dead Space is the current king of survival horror games. The way your kit expands and improves has always been a key ingredient in the best of this genre, and those sparse power nodes always felt like real treasure. It's a system that's absolutely fine as it is, and it will inevitably be changed for the worse by the intrusion of in-game purchases.

I'm sure EA and Visceral Games will say different, but there's no way the presence of microtransactions can avoid influencing its design. If no-one will pay, then why spend time putting it in? If people are going to pay, then how do you manipulate the circumstances to make them? On a project of this magnitude, a feature cannot exist in a vacuum - it warps everything around it to fit. Does that corridor really need to be this long? Why is that rare crafting item hidden in such an out-of-the-way place? Every time you see the little shop prompt, you'll know.

An amazing feature of FF: ATB is that you constantly earn Gil, the FF currency, throughout - yet there isn't a single thing in the game to spend it on. It's like Square are actually mocking the player at times.

This is a difficult subject, because on the one hand publishers will argue players get plenty of hours of entertainment for their money, and in many cases they'd be right. On the other, a game that launches in the standard £40-£50 range is asking for what is quite simply an awful lot of money. Consumers paying that deserve a complete product in return; not one where a central mechanic has been artificially adjusted to squeeze more out. Can you imagine buying Dead Space 3, sitting down to play it in a darkened room, then feeling pressured to go and dig out your bank card?

Amid all the coverage of these events, the pun of the week went to RockPaperShotgun's twitter feed with 'The Grinding of Isaac?' That captures everything about how it feels; the biblical wrongness of grinding, however gently, being introduced into a premium game to eke a little bit more out of your wallet. As many wags this week have pointed out, EA is trying to charge you £40 for an experience, and then charge you more to skip parts of it - a bittersweet joke because, of course, it's true.

It is a great pity that angry gamers are so good at getting het up about pointless things, like Dante's new hairstyle, rather than these game-ruining microtransactions - a bit of real consumer advocacy wouldn't go amiss. Don't we have the right to know if a premium game is built on core systems with a paid-for element? Shouldn't that be marked on its advertising and flagged in its product description? What about specific tools like timelocks? Developers are clearly going to use them, so what's the appropriate response?

The truth is that, for Square Enix and EA, the gamble is quite independent of the specialist press - its success or failure will be determined by the numbers, not any reputational damage on the way. Hoping that these companies make monetisation decisions in an ethical or even a design-led context has ended up here. The market will decide where we go, of course, and one can only hope it spits these experiments back in disgust. Failing that, welcome to the future; where buying a game is an ongoing process.