The problem with a lot of free to play games that use a similar unlock system to Clash Royale is this - what's the point of keeping playing when all of your chest slots are full? You can't unlock anything else, so why should you keep bashing your head against a wall? Rumble Stars Soccer answers that question with one simple retort - because it's a load of fun.

That fun stems from the unpredictability of the game - a good shot can give you a chance for a goal, but a lucky shot could bounce in of its own accord. The randomness inherent here gives everything a hazy tension - you can never be sure who's going to win until the final whistle actually blows.

Keepy uppy

The game is, to all intents and purposes, five-a-side football meets a mobile MOBA. You've got a goalkeeper who, for the most part, stays in place between the goalposts, but your other players are represented by cards along the bottom of the screen. Using those cards costs mana.

That mana regenerates over time, as you'd expect, and when the clock has nearly run out it replenishes even quicker. Different cards have different skills - some might only pass to other team members, others don't care about the ball and will just barge into any member of the opposing team. And there's a cannon as well.

Combining the skills of your players is key to victory. Drop in a dog to grab the ball, then a magnet to suck the keeper away from the goal, and finally toss in a goal-poaching panda to tap in for the score. That's just one of many combos you're going to be using as you learn more and more about your cards.

Rumble Stars Soccer iOS screenshot - Playing at the start of a match

Other times skills and tactics go out of the window and you throw caution and characters to the wind in order to keep the ball from crossing your goal line. Keeping one eye on the other end is key though, because sometimes defensive scrambles can turn into brilliant goals.

You get chests for winning games, all of which take place against other real-life players. In them you'll find new characters and cards you can use to upgrade your players, as well as coins and other currencies to help you along the way.

Progression is a little bit on the slow side, but even when you come up against a stronger player, you're in with a decent chance of causing an upset. And even after a frustrating defeat you're going to jump back in, learn from your mistakes, and try and progress up the ladder.

Golden balls

Rumble Stars Soccer shows that the Clash Royale format isn't as one-note as some clones and copies might suggest. It uses that multiplayer idea as its core, but it builds something weighty and interesting around it that's unlike anything you've played before.

Sure, some might balk at the free to play systems in place here, but the action on offer is some of the sharpest multiplayer that we've seen, potentially since Clash Royale first landed. Get in on this one early, because there's a very good chance it's going to be the next mobile classic.