It's not the greatest of compliments, but after a bumpy start Sea Stars has become my guilty pleasure.

It's an endless-runner that owes a debt to countless others, most notably the in-app purchase-stuffed Jetpack Joyride. Its lack of originality and intrusive freemium model make it hard to like when you first pick it up.

Give it some time, though, and Hothead's bouncy casual charmer will win you over.

Jelly japes

The basic mechanics are immediately familiar. Controlling one of a growing selection of fish as they dash through the ocean, your only input is to hold your finger on the screen to send it swimming towards the seabed.

Let go and you quickly dart back up towards the surface. Build up enough momentum by swimming right to the bottom, and the dash that results when you let you go sends you arcing into the air.

The aim is to time these peaks and troughs so that you avoid Sea Stars's enemy of choice – a collection of jellyfish popping up at random – and pick up as many coins are you can.

It's these coins, in fact, that will determine just how long you play for.

Cash capers

Well, coins or your credit card. Aside from bonuses you encounter in play – clams that give you brief boosts, such as a shield or a sprint – you have to pay for your power-ups, either with the credits you pick up in play or through in-app purchases.

The problem is, even once you've parted with cash to purchase these bolt-ons, further charges await down the line.

Essentially, Sea Stars charges you to unlock each addition, before then taking yet more in-game coins off you when you look to deploy them in play.

It's an approach that's likely to split Sea Stars's audience right down the middle.

For regular players, it's unlikely to be too much of an issue. Coins come so cheaply that those who play regularly will always have enough credit.

But if short stints are all you can manage before being taken down by one of Sea Stars's jellyfish, paying for the power-ups that might give you a fighting chance is the only way you're likely to achieve anything but a quick splash.

Fishy story

Even though this seems like a fundamental fluff, there's no denying that the structure of the game's underwater adventure itself flies by pretty nicely.

Breaking up play are mini-bonus rounds, triggered when you pick up one of the many starfish dotted along the way.

These almost reverse the game's controls in some cases, with any one of three creatures on offer – a crab, a squid, and a bird – picking up your fish and taking charge until you inevitably run into an obstacle.

For instance, when you're picked up by Sea Stars's bird character Molt you just have to tap the screen rather than planting your finger on it, with each touch sending you fluttering briefly skywards.

This variety and the solid, pacey gameplay make Sea Stars a pretty solid entry in the endless-runner genre.

But there's no escaping the feeling that the decent game that lies underneath has been hampered by a rather cynical way of extracting money from you.