As Android phones and tablets have increased in popularity, the number of apps available for the platform has rocketed.
And that means more free Android games. There's a lot of junk out there but, fortunately, there are gems among the junk.
We've worked our way through a whole load of Android games to reveal the ones you should download to your phone.
So without delay, here is our pick of the best free Android games available.
We also have a video run down of the top 10:
1. Angry Birds
The amazingly popular iOS game moved to Android a while ago, earning over two million downloads during its first weekend of availability.
The Android version is free, unlike the Apple release, with maker Rovio opting to stick a few adverts on it rather than charge an upfront fee. The result is a massive and very challenging physics puzzler that's incredibly polished and professional. For free. It defies all the laws of modern retail.
Bebbled is your standard gem-shuffling thing, only presented in a professional style you wouldn't be surprised to see running on something featuring a Nintendo badge with an asking price of £19.99.
You only drop gems on other gems to nuke larger groups of the same colour, but with ever-tightening demands for score combos and scenes that require you to rotate your phone to flip the play field on its head, Bebbled soon morphs into an incredibly complex challenge.
3. Red Stone
There's an awful lot of square-shuffling games on Android and Red Stone is one of the best. And one of the hardest. You start off with a big fat 'King' square that's four times of the normal 'pawn' squares, then set about shuffling things so the fat King can get through to an exit at the top of the screen.
It's hard to accurately describe a puzzle game in the written word, but seriously, it's a good game.
Released in beta form, Newton is a maths/physics challenge that has you lining up shots at a target - but having to contend with the laws of nature, in the form of pushers, pullers, benders (no laughing), mirrors and traps, all deflecting your shot from its target.
The developer is still adding levels to it at the moment, so one day Newton might be finished and might cost money. But for now it's free and a great indie creation.
5. Angry Birds Star Wars
The Angry physics phenomenon took a turn for the weird late in 2012, with Rovio acquiring the rights to blend Star Wars characters with its popular Angry Birds play mechanics. Angry Birds Star Wars is actually pretty nice, with players using Star Wars weaponry to smash down scenery alongside the usual destructive physics action. Not the car crash IP clash we were expecting.
Some might call Drop a game, others might classify it as a tech demo that illustrates the accuracy of the Android platform's accelerometer, thanks to how playing it simply involves tilting your phone while making a little bouncy ball falls between gaps in the platforms. Either way it'll amuse you for a while and inform you of the accuracy of your accelerometer - a win-win situation.
7. Frozen Bubble
Another key theme of the independent Android gaming scene is (ports of) clones of popular titles. Like Frozen Bubble, which is based around the ancient and many-times-copied concept of firing gems up a screen to make little groups of similarly coloured clusters. That's what you do. You've probably done it a million times before, so if it's your thing get this downloaded.
8. Replica Island
Replica Island is an extremely polished platform game that pulls off the shock result of being very playable on an Android trackball. The heavy momentum of the character means you're only switching direction with the ball or d-pad, letting you whizz about the levels with ease. Then there's jumping, bottom-bouncing, collecting and all the other usual platform formalities.
9. Gem Miner
In Gem Miner you are a sort of mole character that likes to dig things out of the ground. But that's not important. The game itself has you micro-managing the raw materials you find, upgrading your digging powers and buying bigger and better tools and maps. Looks great, plays well on Android's limited button array. Go on, suck the very life out of the planet.
Another coloured-square-based puzzle game, only ConnecToo has you joining them up. Link red to red, then blue to blue - then see if you've left a pathway through to link yellow to yellow. You probably haven't, so delete it all and try again.
A brilliantly simple concept. ConnecToo used to be a paid-for game, but was recently switched to an ad-supported model - meaning it now costs you £0.00.
Once you're successfully rewired your brain's 25 years of playing Tetris in a certain way with certain buttons and got used to tapping the screen to rotate your blocks, it's... Tetris.
It hinges on how much you enjoy placing things with your phone's trackball or pad. If you're good at it, it's a superb Tetris clone. Let's hope it doesn't get sued out of existence.
UPDATE: While Titres seems to have been removed from Google Play, there's now an official Tetris app available to download.
Not the best-looking game you'll ever play, with its shabby brown backgrounds and rudimentary text making it look like something you'd find running on a PC in the year 1985. But Trap! is good.
You draw lines to box in moving spheres, gaining points for cordoning off chunks of the screen. That sounds rubbish, so please invest two minutes of your time having a go on it so you don't think we're talking nonsense.
Coloured gems again, and this time your job is to switch pairs to make larger groups which then disappear. That might also sound quite familiar. The good thing about Jewels is its size and presentation, managing to look professional while packing in more levels than should really be given away for free.
We had to put one Sudoku game in here, so we'll go with OpenSudoku - which lives up to its open tag thanks to letting users install packs of new puzzles generated by Sudoku makers. It's entirely possible you could use this to play new Sudoku puzzles for the rest of your life, if that's not too terrifying a thought.
Abduction! is a sweet little platform jumping game, presented in a similarly quirky and hand-drawn style as the super-fashionable Doodle Jump. You can't argue with cute cows and penguins with parachutes, or a game that's easy to play with one hand thanks to its super accessible accelerometer controls.
16. The Great Land Grab
A cross between a map tool and Foursquare, The Great Land Grab sorts your local area into small rectangular packets of land - which you take ownership of by travelling through them in real-time and buying them up.
Then someone else nicks them off you the next day, a bit like real-world Risk. A great idea, as long as you don't mind nuking your battery by leaving your phone sitting there on the train with its GPS radio on.
17. Brain Genius Deluxe
Our basic legal training tells us it's better to use the word "homage" than to label something a "rip-off", so we'll recommend this as a simple "homage" to the famed Nintendo Brain Training franchise.
Clearly Brain Genius Deluxe is not going to be as slick, but there's enough content in here to keep you "brain training" (yes, it even uses that phrase) until your battery dies. The presentation's painfully slow, but then again that might be the game teaching you patience.
Coloroid is aery, very simple and has the look of the aftermath of an explosion in a Tetris factory, but it works. All you do is expand coloured areas, trying to fill them in with colours in as few moves as possible - like using Photoshop's fill tool at a competitive level.
Cestos is sort of a futuristic recreation of curling, where players chuck marbles at each other to try and smash everyone else's balls/gems down the drain and out of the zone. The best part is this all happens online against real humans, so as long as there's a few other bored people out there at the same time you'll have a real, devious, cheating, quitting person to play against. Great.
20. Air Control
One of the other common themes on the Android gaming scene is clones of games based around pretending to be an air traffic controller, where you guide planes to landing strips with a swish of your finger. There are loads of them, all pretty much the same thing - we've chosen Air Control as it's an ad-supported release, so is technically free.