Fertile ground for experimentation, indie games have transformed the industry over the last two decades, delivering more huge innovations and disruptive new paradigms than a lifetime of triple-A military shooters. Don't believe us? Check out some of the games on this list and think about the impact they've had on the games you play today.
Counter-Strike (1999)
Originally developed as a Half-Life modification in the late 90s by developers who later joined Valve off the back of its success, Counter-Strike wasn't the first team deathmatch game, by any stretch, nor the first to utilize realistic weaponry, but its innovations were numerous and powerful. Setting terrorists against counter-terrorists, it built gameplay around asymmetrical bomb defusal and hostage rescue scenarios, which was unusual outside of novelty game modes at the time. It also had an in-game economy that rewarded effective play with better weapons, allowing consistent teams to snowball their opponents, and its decision to make dead players sit out the rest of the round was genius.
Counter-Strike has inspired plenty of pretenders over the years, and hugely successful series like Call of Duty owe a lot to its ideas. The latest version, Counter-Strike: Global Offensive, is still hugely popular - thanks in part to Valve's innovative cosmetic item market - and now reigns supreme as the most popular competitive first-person shooter in the world, with esports tournaments worth $1m+ in prize money happening multiple times a year. Having cast a long shadow once, it will to do so again as esports grows in the next decade.
Trials 2: Second Edition (2008)
There are plenty of other bastard-hard indie games we could have identified here - the whole strata of retro-visual 2D platform games like N+ and Super Meat Boy, for example - but we felt like going with Trials because, well, we love it the most. RedLynx's 2D trials bike game is about climbing over obstacle courses on a motorcycle, using the gas and brakes as economically as possible to give you the friction and momentum you need without unseating your rider. The whole thing seems to take place in a dark warehouse, too, which gives it a really grungey feel, and when your rider falls off and tumbles around in physically horrendous fashion, you half wonder if anyone will ever find him.
This version preceded the much more successful Xbox Live Arcade version, Trials HD, and its many successful follow-ups, including the particularly brilliant Trials Evolution, but it already had many of the series staples, including global leaderboards, the ability to instantly reset yourself to the last checkpoint or the start of the track at the touch of a button, and absolutely fiendish track design in the latter stages. Back in the 90s we used to talk about "one more go" games, and Trials 2: Second Edition not only epitomized that kind of gameplay, but arguably re-popularized it as well.
Minecraft (2009)
When Markus "Notch" Persson released the first version of Minecraft in 2009, he allowed people to play for free and asked dedicated fans to cough up a small fee for the "indev" version, where he rolled out new updates. Before long its success took over his life. In 2014, he sold the company that owned and continued to develop Minecraft, Mojang, to Microsoft for $2.5 billion. Unfortunately he then retired to live out his days in a Hollywood mansion tweeting increasingly deranged things at his millions of followers, but for all his latter-day sins, the game that he left behind remains one of the most influential since Mario Bros.
Do we really need to explain Minecraft? You are dropped into a procedurally generated world and encouraged to gather resources and craft things out of the terrain, which it turns out is built out of unassailably cute little 3D cubes. Some people work together on the same server, building everything from cathedrals to spaceships, while others dig around solo, juggling survival and creation across endless days and nights.
Minecraft itself has been ported to every platform imaginable and spawned numerous extensions, like Story Mode, while its general gameplay cycle of crafting and survival has certainly trickled out into a few other indie games. But its larger, untold legacy probably lies in the future actions of a generation of children and teens, who lost themselves to Minecraft's Lego-like crafting and saw, through this game, how far their imaginations might one day be able to carry them.
Geometry Wars: Retro Evolved (2005)
It might be a stretch to call Geometry Wars an indie game - it was developed by Bizarre Creations, who were owned by Microsoft at the time - but the fact that it was largely the work of one designer, Stephen Cakebread, who originally toiled away on it as an unlockable mini-game for Project Gotham Racing 2, gives it that outsider edge we're looking for.
The revamped Xbox 360 version, Retro Evolved, meanwhile, was one of the games almost singularly responsible for establishing Xbox Live Arcade as one of the principal successes and innovations of that console generation. As critics and new Xbox 360 owners struggled to find gripping experiences among the initial salvo of 360 titles, we found ourselves turning more and more to the likes of Geometry Wars and Hexic HD. Before long, we realised that the fact we were playing them more than traditional AAA games wasn't just a blip - it was part of a new world order. Weekly Xbox Live Arcade releases became a real event, peaking with the likes of Braid and Fez, both of which proved very influential as well.
Xbox Live Arcade doesn't really exist in the same form any more, but it helped change the way we think about small games sold exclusively through digital distribution, and - perhaps fittingly for a twin-stick shooter about blasting weird space microbes in the confines of a galactic petri dish - Geometry Wars: Retro Evolved was the catalyst.
Canabalt (2009)
A few years after the advent of the smartphone, it was clear that games were going to be a huge part of its long-term success, but attempts simply to port existing console and PC game ideas to devices that lacked any physical buttons were meeting with mixed success. Often the games looked great, but controlling them was awkward and counterintuitive. Canabalt, the first hugely successful side-scrolling endless runner, changed that.
Developed by Adam Saltsman as part of the Experimental Gameplay Project, Canabalt was about a dude running from left to right, occasionally jumping. The sole interaction was activating that jump, by tapping the screen. It sounds incredibly basic, but the frantic pace and hectic environments made for an addictive experience.
Other mobile game developers clearly agreed, because within a few years you couldn't move for endless runners on the various mobile app stores. Some took the concept and, uh, ran with it, like Temple Run, which involved guiding an Indiana Jones-like figure in third-person past obstacles, jumping, ducking and even turning left and right now and then. The ultimate tribute arrived last year though, when Nintendo's first serious mobile title, Super Mario Run, adopted the auto-run-and-tap-to-jump mechanic. When Shigeru Miyamoto starts borrowing your ideas, you know you can probably call it a day.
DayZ (2013)
PlayerUnknown's Battlegrounds, eh? Obviously Brendan Greene's phenomenally successful Early Access multiplayer shooter owes a lot to the movie adaptation of Battle Royale, as well as his own work with H1Z1 and as a modder, but the original unlikely success story in this brutal survival genre was Bohemia Interactive's ArmA 2.
ArmA 2 was an incredibly exacting military simulation - the sort of game in which flying a helicopter really does involve reading a flight manual - when New Zealander Dean Hall decided to adapt its huge post-Soviet environment of Chernarus into a zombie survival space. The result was a rickety modification that took great patience to set up and then find a working server. Despite this, it was an overnight sensation, propelling ArmA 2 to sales beyond Bohemia's wildest dreams, and making a celebrity out of Hall.
DayZ had that lightning that all these games try to bottle: "emergent" situations, where the mechanics of the world, which allow for interaction and don't encourage or discourage particular behaviors, led to fascinating outcomes. You might make friends with another player, who would fix you up and help you repel a zombie horde, only to then slaughter you and steal your things just when he or she earned your trust. Or you might find yourself staring down the barrels of a roving party of other players, who planned to murder you and take your things, only for them to become overwhelmed by zombies, allowing you to slip away. DayZ soon span off from ArmA 2 itself, and inspired a raft of pretenders, many of which were hugely successful themselves. Rust, for example, clearly owes some of its DNA to DayZ. PUBG is just the latest beneficiary, and it will be interesting to see what other exciting new games continue to echo DayZ's great work in years to come.
Dear Esther (2012)
It wouldn't be a list of 21st century indie games without a so-called "walking simulator", and Dear Esther was arguably the one that started them all. Good luck finding us a review of this game that doesn't include at least passing reference to the debate about whether it even qualifies as a game - even the Wikipedia page offers a slightly brutal appraisal when it puts "gameplay" in air quotes in its description of what you do. But bickering about whether Dear Esther qualifies as part of this artform is about as useful and interesting as all the equivalent debates about new forms of music and literature have been down the years - they say more about the imaginations of the people vocalizing them than they do about the art at hand. Dear Esther may not include traditional gameplay mechanics beyond walking and looking around, but there's surprising depth here and it will stay with you for longer than plenty of games that cost several hundred million dollars to make.
It is a basic setup, as many good things are - you explore a Hebridean island listening to an anonymous individual reading letter fragments to a woman named Esther. It's a clever synthesis of story and location, revealing things about the author and the place as you move around, and each new location and the quirks of the spaces you explore raise questions and invite you to fill in the answers based on your observations. It won't be for everyone, but then neither is FIFA. If you are looking for a change of pace in an interactive environment that uses different muscles than the ones you usually bring to bear in video games, Dear Esther remains a deeply affecting experience. Just ask the legion of developers who followed successfully in its stead, from The Stanley Parable and Gone Home to Firewatch and The Vanishing of Ethan Carter. Dear Esther was the atom at the center of what became a universe of masterpieces.
No Man's Sky (2016)
We will always have a soft spot for No Man's Sky, whatever the haters say. The thrill of breaking atmosphere on a new world and carving our way through thinning layers of space dust to the mysteries of the surface below always had a healing effect on us, rather than the enraging one it appeared to have had on a lot of folks on the internet. Whatever our feelings, though, it feels safe to say that No Man's Sky carried a big lesson for other indie developers about the best way to handle hype.
It isn't entirely Hello Games' fault that the first trailer for No Man's Sky inspired so much unchecked imagination, but the subsequent year and a half of boundless optimism about what would be possible in this procedurally generated universe definitely looks like a cautionary tale in hindsight. However excited you are about your game, it's important to keep other people's expectations in check. It was only in the days immediately before the game arrived when Hello Games' Sean Murray did a last round of interviews and talked about how No Man's Sky was "a very chill game", "a niche game" and "maybe isn't the game you imagined from those trailers".
By then it was too late - the damage was done, and rather than blown minds, a legion of expectant fans ended up with blown fuses. We enjoyed that chill game, and we suspect that, had Hello Games had been clearer about what kind of game it was in the months before it came out, not just the last few minutes, we might have found more people sharing that perspective.