The best mobile games balance depth and simplicity. You can pick them up and in a few minutes you know pretty much exactly what's going on, but after an hour or so you realise there's a lot more to it than you thought.
Clash Royale walks that line brilliantly. At first glance it's an easy to understand mix between a tower defence game and a MOBA.
But once your teeth start sinking into the fleshy bits under the Supercell polish, you'll find an engaging and addictive experience that's not afraid to stride out on its own.
What's the dealio then?
As you might expect, this is set in Supercell's Clash of Clans universe. If you've ever played that game, or even watched one of the adverts, then you're going to have a pretty decent idea about the shenanigans bubbling under the game.
In gameplay terms, it's a two lane MOBA. You've got three towers – two small ones to the left and right of the screen, and then your King tower in the middle behind them. Your opponent, who's a real person, has the same set up opposite you.
It's your job to send out different troops, represented by a stack of cards at the bottom of the screen. You drag the card where you want to deploy your units, then release it.
These cards have different elixir costs, and much like a tower defence game, your elixir regenerates over time.
As well as troops you've got spells and buildings at your disposal. They're deployed in the same way, and cost elixir too.
Each card you play has strengths and weaknesses, and learning the roles of them is important to kicking some ass.
The game adds an extra twist in the last minute as well. With sixty seconds left your elixir starts recharging furiously, meaning both you and your opponent can start throwing out units left right and centre.
It makes for a frantic final scramble, and often all the good work you've done in chipping away your enemy's towers in the first two of minutes is undone in the chaos of the last one.
The fights ebb and flow brilliantly. They might only last three minutes, but there's a lot of tactical decisions to be made on the fly, and figuring out which cards to take into a battle can be the difference between success and crushing defeat.
But this is free to play yeah?
Yup, but there's no energy system. There are wait timers on the chests you earn, which contain cards and coins, but that's it. So long as you've got an internet connection you can jump in and smash as many faces as you want.
And you'll want to smash a lot of faces. The compulsion loop here is dangerously tight. You can easily lose hours in the quick-paced battles, and hours more balancing your deck to try and make sure you can take on all-comers.
Even if you're not a fan of Clash of Clans, Clash Royale is well worth a look. It's an incredible amount of rewarding fun, it's nail-biting at times, and there's content here that will keep you busy for weeks if not months.