There’s about an hour of magic at the beginning of Harry Potter: Hogwarts Mystery, when an owl arrives from Dumbledore with a letter bearing your name and you’re whisked off to Diagon Alley to prepare for your wizarding education. Like a lot of smartphone games, Hogwarts Mystery looks a bit basic, but it’s not lazy; it’s colourful and gently humorous. Fan-pleasing touches come in the form of dialogue voiced by actors from the Harry Potter films, cameos from beloved characters and allusions to nuggets of Potter trivia.

The enchantment fades when you get to the first story interlude, where your character becomes tangled up in Devil’s Snare. After a few seconds of furious tapping to free yourself from its clutches, your energy runs out and the game asks you to pay a couple of quid to refill it – or wait an hour or for it to recharge. Sadly, this is absolutely by design.

From this point onwards Hogwarts Mystery does everything it can to stop you from playing it. You cannot get through even a single class without being interrupted. A typical lesson now involves 90 seconds of tapping, followed by an hour of waiting (or a purchase), then another 90 seconds of tapping. An outlay of £2 every 90 seconds is not a reasonable ask. Between story missions the wait times are even more egregious: three hours, even eight hours. Hogwarts Mystery pulls the old trick of hiding the true cost of its purchases behind an in-game “gem” currency, but I worked out that you’d have to spend about £10 a day just to play Hogwarts Mystery for 20 consecutive minutes. The interruptions prevent you from forming any kind of attachment to your fellow students, or to the mystery at the heart of the story. It is like trying to read a book that asks for money every 10 pages and slams shut on your fingers if you refuse.

Without the Harry Potter trappings the game would have nothing to recommend it. The lessons quickly become dull and the writing is disappointingly bland, though it does make an effort with character dialogue. Duelling other students and casting spells are fun, but most of the time you’re just tapping. Aside from answering the odd Potter-themed question in class, you never have to engage your brain. The waits would be more bearable if there was something to do in the meantime, like exploring the castle or talking to other students. But there is nothing to find at Hogwarts, and no activity that doesn’t require yet more energy.

Harry Potter is a powerful enough fantasy to override all that, at least for a while. The presence of Snape, Flitwick or McGonagall is just enough to keep you tapping through uneventful classes and clear effort has gone into recreating the look, sound and feel of the school and its characters. But by the time I got to the end of the first year I was motivated by tenacity rather than enjoyment: I WILL play this game, however much it tries to stop me. Then came the deflating realisation that the second year was just more of the same. I felt like the game’s prisoner, grimly returning every few hours for more thin gruel.

What is sad is that it’s so unnecessary: Harry Potter fans would need little encouragement to spend a few quid here and there on clothes or wands to customise their characters, and there are countless examples of free-to-play games that offer players the option to spend money without ruining the experience (Fortnite, Pokémon Go and Dandy Dungeon, to name three). Hogwarts Mystery’s best chance for redemption would be if developer Jam City pulled back on the absurd timers in an update – but you get the dispiriting sense that the game was designed around them.

But even if the time restrictions were removed, it wouldn’t fix the paucity of things to do in virtual Hogwarts. Harry Potter: Hogwarts Mystery is a dull game with a great concept, made borderline unplayable by its hyper-aggressive monetisation.

• This article was amended on 8 May 2018 to note that the game interrupts your play rather than refuses to let you play.