By the time The Walking Dead reaches an end, I'll have shelled out around £20 for the pleasure - far more cash than I'd have been willing to splash if I'd been asked for it all in one chunk. The episodic nature of The Walking Dead makes this partwork structure a particularly natural fit, but I'd say there's good reason to start selling games with this method elsewhere.
Games that cost £40 might appear to offer value, but that only applies if you play the whole thing. If you get bored and wander off after five hours, you're left with a rather expensive mistake. The beautiful thing about The Walking Dead is that I can lose interest whenever I choose to. I'm only invested for three hours at a time, and this should also benefit the quality of the series: if the standard takes a nosedive halfway through the series, Telltale is likely to see sales dip.
Bang On Target
There's a pricing sweet spot for online purchases that hovers just beneath the five pound mark. Smartphone users will be well aware of this - count the number of games you've spent money on and consequently barely played. The Walking Dead and Dead Rising: Case Zero have more in common than just zombies: they both seem to argue that the demo is dead. Given the choice between a free ten-minute trial and a couple of hours for a couple of quid, I'm far more willing to make the small investment for the bigger payoff.
Tiny in-game purchases aren't anything new, but these traditionally offer end-game goodies. Episodic games like The Walking Dead point out that this doesn't make sense: why rig it so the stuff that only costs a few quid is only available to those who've already spent £40, when all those little purchases will most likely add up to so much more?