Welcome to the latest in our series of Pocket Gamer columns. We're taking the best games writers in the industry and giving them a platform. Veteran journalist Jon Jordan is here each week examining the trends shaping your mobile games scene. This week, he's playing - and waiting in - Harry Potter: Hogwarts Mystery.

I'd call it a fallacy or a misunderstanding, but one of the most popular criticisms of free-to-play mobile games is their use of energy systems to gate players' progress.

The situation is clear. You want to keep playing - race another car, fight another battle etc - but you don't have any more gas or mana.

The choice is stark; either spend some money to keep playing or wait until your energy meter refills. Obviously, you feel annoyed. You were playing happily and now your flow is broken.

The developer has taken away your fun and you leave the game in a bad mood. In psychological terms it's a classic case of the negative impact of having something you feel is yours taken away from you.

And it doesn’t matter you'd been thoroughly enjoying the game for 15 minutes beforehand.

The power of snacking

The fact is, as human beings and for entirely logical reasons, we are highly tuned to the experience of present events and the anticipation of future events. Past enjoyment isn't really taken into account.

So, in this regard, I'd partially agree with the criticism of in-game energy systems. They are often badly implemented in terms of game design and psychological experience, as well as being fairly ineffectual in terms of monetisation.

And this is why energy systems are very carefully used in well designed F2P mobile games. But they are still used, because they are fantastic at educating players about a game's inherent play session length and encouraging them to come back and play daily (i.e. retention).

A good example is in Jam City’s just-released Harry Potter: Hogwarts Mystery, which has been generating some controversy.

Set in the Wizarding World, it's a high quality production with a strong narrative arc which takes players through seven years of education at Hogwarts, learning spells, making friendships, and ultimately trying to solve the mystery of what happened to your brother.

Of course, it could have been designed and released as a classic adventure game, but given the cost of development and the licence, it would have been priced $20 and the small number of players who bought it would have complained it "only took them 8 hours to finish".

Slowly, slowly puppydog

Instead, as an F2P mobile game, millions of players can play the opening minutes and see if it's a game they want to invest more time in.

The energy system (and overall game design) ensures players can't burn through the main narrative arc in 10 hours.

In this way it provides pacing. "Come back and play some more in a couple of hours," the game suggests - or informs you if you've enabled push notifications. And this is exactly how people interact with their mobiles.

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Jam City has released a game anyone who doesn't take immediate affront about waiting for their energy to refill and delete, has the potential to enjoy for weeks, months and years, as more content, characters, side quests and perhaps even mysteries are added.

Hence making games time-based brings players more pleasure in the long run. Given the power of anticipation, this is something developers need to better highlight, especially given current usage trends when it comes to binge-watching entire TV 'box sets' in a weekend.

Because, conversely, even if you had the money to instantly complete every single mission in Hogwarts Mystery and burn through all the narrative content, you would have spent a enormous amount of money and only experienced a fraction of the fun.

If this column has given you food for thought, share your comments below and bookmark Jon Jordan's page for more of the same next Monday. Remember to also check out words of wisdom and mirth from experienced games journalists Susan Arendt and Harry Slater each week.

Want more? Check out our growing collection of Harry Potter: Hogwarts Mystery features!