This list has been updated to include Hearthstone: Heroes of Warcraft.

Whether you play games all the time or just want something to fill a few quiet moments here and there during the day, passing the time doesn't need to be expensive.

Yes, you need to break out your wallet if you want the latest big AAA shooter, but the free route is becoming increasingly interesting. Many older games are now opening out in search of a wider audience, and more and more companies are finding ways to profit from free releases.

For indie developers, it's the perfect way to make a name for themselves, either just for the glory or to build an audience for future games.

US company 2D Boy, for example, launched onto the scene with Tower of Goo, a game that involves building a tall tower out of bouncy balls of stretchy slime. This free download morphed into the amazing full title World of Goo, which took the net by storm.

We've gathered together 40 of the best free games around, covering releases new and old from every genre. With so much choice, you're guaranteed to find at least one you like. Give them a go - there's nothing to lose.

1. Planetside 2

Download Planetside 2

Planetside 2 is an epic, all-out battle so ridiculously impressive, you'll give yourself a quick pinch every time you remember it's completely free. There are in-game purchases of course, but you can still dive into gaming's biggest ever battlefield and be useful using just default gear.

Best free games - Planetside 2

There's simply nothing like taking part in a massed assault on an enemy base and coming out on top, or living in a world where an enemy convey could appear on the horizon at any second. If you need any proof that 'free' doesn't mean making compromises any more, Planetside 2 will provide it.

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2. Dota 2

Download Dota 2

Technically Dota 2 is in closed beta, but there are so many codes flying around the net that it may as well be open at this point. Even if it takes a quick request on a forum though, Dota 2 is a phenomenon you should at least play to experience, and now is a good time.

Best free games - Dota 2

A brief tutorial now points out the ropes, with Steam Community stepping in to provide guides to the original MOBA/whatever-you-want-to-call-this-genre-if-not-MOBA.

Don't expect a warm welcome or easy learning curve from this surprisingly complex game, but bring a few friends and you have a good chance of being hooked on one of the biggest crazes in PC history.

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3. Hawken

Download Hawken

Jump behind the controls of your own mech and fight it out in a gloriously realised future world with Hawken. They're the 'agile' kind of mech rather than the slow lumbering tanks of MechWarrior Online, so purists should head there instead, but still a change of pace from blitzing around in soldier uniforms with automatic rifles.

Best free games - Hawken

Expect to pay to upgrade your starter mech if you enjoy the action, but you can jump in and get the flavour of the thing without paying a single penny.

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4. Super House Of Dead Ninjas

Download Super House Of Dead Ninjas

One of the most enjoyable Flash games in recent memory, which is also available as an expanded commercial-but-cheap release on Steam if you fancy more toys and full-screen action.

The free version of Super House Of Dead Ninjas always feels like a complete game in its own right though though, as you guide the Crimson Ninja from the top of a demon-infested tower to the horror waiting at ground floor.

Best free games - Super House Of Dead Ninjas

Randomly generated adventures keep things fresh, with the speed of the action more a challenge than any individual enemy. You can handle any situation in front of you. You just don't get to stop to catch your breath. Ever. Until you die, of course.

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5. Star Wars: The Old Republic

Download Star Wars: The Old Republic

Almost but not quite breaking the land-speed record from subscription to free-to-play MMO, but EA's loss is your gain. Star Wars: The Old Republic has some irritating restrictions that may chafe after a while, but you can play all eight of its class stories from start to finish and dive into the online content for free.

Best free games - Star Wars The Old Republic

It's worth the download simply to experience the Star Wars universe from different perspectives, like the hyper-professional Imperial Agent and Bounty Hunter. If you want to go with the dull option and just have a generic Jedi Knight though, that's fine too.

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6. Super Crate Box

Download Super Crate Box

Dullest name in the world? Possibly! Super Crate Box makes up for it, though, with a simple mechanic that's far more fun than it has any right to be. How long can you last against a stream of incoming monsters? It probably depends whether you're fighting them off with a pistol or a rocket launcher.

Best free games - Super Crate Box

The catch is that you don't score points for killing, but collecting crates - and every crate gives you a different weapon. And not killing the monsters only makes them crosser. It might not sound like much, but its speed and difficulty will keep you hooked from the off.

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7. World Of Tanks

Download World Of Tanks

World of Tanks is a different kind of MMO - the clue being in the title. Team based, massively multiplayer action with a huge range of war machines to drive into battle awaits, with new players able to join the action immediately.

Best free games - World Of Tanks

An upgrade system adds a sense of personalisation, while being surrounded by a whole army constantly reminds you that loners don't do well on the battlefield.

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8. Smite

Download Smite

Gods from around the world get together to battle it out in a Dota/MOBA inspired clash of divine vengeance in Smite.

Best free games - Smite

The camera is behind the characters this time, making for a more direct connection to the action than simply guiding your lord around with a mouse, but the premise will be either familiar if you've played its inspirations or a way to get the feel for the style if you haven't. Gods include Zeus, Thor, Kali, Artemis and... Cupid? Well, at least he has his own bow...

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9. Ultima: Worlds Of Adventure

Download Ultima: Worlds Of Adventure

Two blasts from the pasts that suffer from an outdated interface, but are still worth checking out for being RPGs that dared explore new settings. Savage Empire is an adventure into pulp fiction of the Doc Savage style, with the Avatar of Ultima fame being pulled into a lost world.

Best free games - Ultima Worlds Of Adventure

Martian Dreams imagines a world where the Victorian era's greatest minds accidentally get shot to the Red Planet and discover more than canals waiting to greet them. If these give you a taste for the Ultima experience, the rest of the games are also on the site for not much money.

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10. Black Mesa

Download Black Mesa

Remember a little game called Half-Life? It was quite popular. Black Mesa Source is the long-awaited rebuild of it in Valve's Source engine, and a must-play for any fan of the series.

It's not simply a pixel-for-pixel recreation, but a re-imagining of it - adding detail so seamlessly that you'll forget how primitive the original was, as well as a few extra elements of its own, like female Black Mesa scientists.

Best free games - Black Mesa

Only the final chapter, Xen, remains unfinished, due to needing more work to make that part of the original actually'good. There's no ETA yet, but we can't wait.

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11. Runescape

Download Runescape

Runescape is one of the biggest free-to-play MMOs out there, and now would be a good time to take a look. The long awaited sequel is due in Summer, so you'll be able to fully appreciate the improvements to narrative, graphics, and and general world design.

Best free games - Runescape

It's certainly not the shiniest MMO in the world in its current form, but hanging onto this many players shows it's doing something right. It also has the advantage of being playable in a browser, and thus playable anywhere you have Java. Not to be confused with "Run! Escape!", which is what you should do if chased by an angry velociraptor.

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12. Barkley Shut Up And Jam Gaiden

Download Barkley Shut Up And Jam Gaiden

Retro RPG madness meets absolutely all of the drugs in this crazy adventure. Here are just a few details. Barkley Shut Up And Jam Gaiden is set in post-cyberpocalyptic Neo New York.

You're basketball player Charles Barkley, retired from the game after killing an audience with an epic power dunk. Now, the world is in double-peril as a second Chaos Dunk nukes much of New York. Then it gets weird.

Best free games - Barkley Shut Up And Jam Gaiden

There's a sequel coming thanks to Kickstarter. It asked for $35,000. It got $120,335. There are reasons why people want that sequel. You should get ready for it.

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13. Wonderputt

Download Wonderputt

There are games that excite and games that teach - and sometimes, games that are simply lovely. Wonderputt is one of those - a perfectly formed round of mini-golf on a map that keeps unfolding out and revealing its surprises.

Best free games - Wonderputt

Calming, absorbing, even a little bit magical, and the perfect way to kill a couple of quiet hours with a soft smile and gentle sound of mouse clicking.

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14. League of Legends

Download League of Legends

Pick your champion and head into battle in this amazing free-to-play game from the creators of DOTA. League of Legends' automated matchmaking, range of characters and excellent maps have made it a multiplayer star over the last year, and one well worth a play.

Best free games - League of legends

It's a very aggressive game to play, but one that rewards good team work and careful tactics. Don't expect to master it overnight, but it won't be long before you're having fun.

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15. Lord of the Rings Online

Download Lord of the Rings Online

Many MMOs are being launched or relaunched as free-to-play at the moment, but Lord of the Rings Online is one of the ones that most warrants a second look. Not only is it an excellent game in its own right, it's one of the more mature MMOs out there.

Best free games - Lord of the rings online

You will likely have to pay eventually, if only to unlock adventure packs, but there's no subscription fee and nothing to buy up-front. If you missed it at launch, it's time to give it a try.

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16. Sarien.net

Download Sarien.net

Remember the Sierra adventures of old? Sarien.net makes them multiplayer. At least, partly. Technically, you still play on your own, but can see other players wandering around the world as you do. It has access to King's Quest, Space Quest, Police Quest, and a lesser known game, The Black Cauldron.

Best free games - Sarien

We've hesitated to mention this one before due to legal questions over it, but now it's been officially approved by Activision, there's nothing stopping you from jumping right in.

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17. Quest for Glory II VGA

Download Quest for Glory II VGA

Technically, we should probably be mentioning King's Quest III Redux, just released by the same group of developers... but Quest for Glory II is a much better game than King's Quest III ever was, so if you only play one, play this.

Best free games - Quest for glory ii vga

It's an adventure/RPG hybrid that can be played as a Warrior, Magic User or Thief, with each path unlocking new challenges and opportunities. It's funny, exciting, and incredibly open, and one of the most beloved adventure games ever made - both in its original form, and in this more recent remake.

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18. Battlestar Galactica

Download Battlestar Galactica

The official Battlestar Galactica MMO is interesting for two reasons - it plays in the browser (and looks pretty good), and it's completely free to play. That's unusual for any licensed game, although as ever, the words 'free to play' have the words 'with optional purchases' slapped right onto the end.

Best free games - Battlestar galactica

The story is that both Galactica and the Cylons have been blasted into a new area of space by a mysterious bit of technology, and now both sides are fighting over outposts and control points. You can choose either, with a bit of wandering around the ships, and lots of mouse-based space combat and mining.

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19. Minecraft Classic

Download Minecraft Classic

Minecraft. It's the game everyone's talking about/won't shut up about. But there's a reason for that, and you can get a taster of it for free. Minecraft Classic simply lets you build things, without monsters or item crafting getting in the way.

Best free games - Minecraft classic

The latest version isn't expensive though, if you do find yourself bored with having an unlimited canvas to play with. There's not much more to it than that, but that's all Minecraft needed to become one of the most successful games on the internet. Find out why, if you haven't already.

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20. Zuma Blitz

Download Zuma Blitz

Most Facebook games aren't much fun. Zuma Blitz might just go too far the other way. It's all the fun of regular Zuma - shooting balls before they get all the way round a track - but now bolstered with high-score tables devoted to your friends, new toys to unlock, and a weekly reset to keep you playing.

Best free games - Zuma blitz

You might need to squint a bit on high-resolution screens, but the satisfying click of a shot landing into place never starts feeling old. There are paid-for-items if you want to boost your performance, but you can easily play without.

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21. Mr. Smoozles Goes Nutso

Download Mr. Smoozles Goes Nutso

A simple but fun little maze game, mixed with a little adventuring, and a whole bucket worth of personality. (Okay, we're mostly including it because of the title.) Aliens are invading and have turned Mr. Smoozles the cat into their psychotic stooge. You have to avoid him, rescue your friends and foil the invasion.

Best free games - Mr smoozles goes nutso

It's based on a webcomic series, but you don't need to know anything about it to follow the action. This used to be a commercial game, but was made freeware to celebrate the author's 18th anniversary in the industry.

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22. Tyrian 2000

Download Tyrian 2000

Technically, it's been freeware for a while now, but Good Old Games' re-release of it in December 2010 breathed new life into one of the PC's most beloved shooters. Tyrian 2000 offers loads of levels, a ridiculous amount of ship customisation, and some of the best easter eggs around.

Best free games - Tyrian 2000

If you get bored of the top-down shooting, try typing 'destruct' at the title screen to see its weapons-grade version of the classic Scorched Earth. Alternatively, unlock the ship that looks like a carrot, and banana bomb your way to victory.

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23. Marathon Trilogy

Download Marathon Trilogy

Before Halo, there was Marathon - Bungie's FPS series on the Mac. Now that Halo Reach has brought an end to the series (at least for the moment), why not celebrate with a trip back to see where it all started?

Best free games - Marathon trilogy

Bungie has made Marathon completely free, and with an open-source app, called Aleph One, it's playable on the PC as well. You'll need to download quite a few files, but your reward will be an admittedly very old-school FPS that puts more of a focus on narrative than you might expect, where much of Bungie's philosophy was born.

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24. Tribes: Ascend

Download Tribes: Ascend

Easily the best shooter designed for free-to-play action, and a very respectable follow-up to the classic. Don your jetpack and launch into battle across huge maps, with weapons that take real skill just to land a hit - never mind a kill.

Best free games - Tribes: Ascend

Tribes: Ascend fast, furious, and absolutely brilliant, and there's no reason to spend any money in the in-game shop if you simply want to hold your own in battle. Though there's plenty of stuff to buy if you do...

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25. Team Fortress 2

Download Team Fortress 2

It may be five years old, but nothing offers so much crazy fun. Unlike most shooters of its age, players are still there to have a good time rather than hurl abuse at newcomers, and there's no shortage of cool toys to do so with. Endlessly silly and amazingly fresh, it's still one of the shooter genre's kings, free to play or not.

Best free games - Team fortress