10. NetHack
Get it from the official website.
Why it makes the list: Nethack was developed in 1987. And in all the years after that up until 2003. It's a traditional roguelike, again complete with brutal perma-death and ASCII graphics, the product of collaborative development over a huge amount of time. This is a game all about discovery, and many have scoured its dungeons for years attempting to find all its secrets. It's an undisputed PC classic.
9. Beneath a Steel Sky
Why it makes the list: With the launch of Good Old Games in 2008, this classic cyberpunk adventure - from point-and-click masters Revolution Software - lost its price tag. While it's certainly dated now, Beneath a Steel Sky is a masterful work of storytelling, complete with decent puzzles to boot, and blows many modern adventure games - ones with very real prices attached - out of the water.
8. Passage
Why it makes the list: There are those who would say Passage isn't worth your time. It's over in five minutes, and there's only minimal interaction. But this small but beautifully constructed art game from Jason Rohrer - who went on to make Sleep Is Death, picking up a 90% score in PC Gamer in the process - is surprisingly moving for a thing of its size. The game asks what you want out of life, and then shows you how the passage of time will make this play out as you wander from left to right towards the inevitable. A lovely thing.
7. Digital: A Love Story
Why it makes the list: Budding writer Christine Love emerged out of nowhere to create a computer game last year. Part Uplink-alike, part visual novel, Digital tells the story of a lonely teenager in the late 1980s, sitting in front of a computer at the dawn of the internet. There are basic puzzles littered throughout, but this is mainly about the fantastic presentation of the story, and the strikingly original touches Love has bestowed upon it. An hour of gorgeously crafted, personality-imbued indie gaming.
6. System Shock Portable
Get it from the System Shock Mods Archive.
Why it makes the list: System Shock 2 might get all the plaudits most of the time, but the original 1994 game can still hold its own. It's a tense, forward-thinking action adventure that did things most shooters weren't even dreaming of at the time - like trying to tell a complex and involved story, for example. Since it's effectively been deemed abandonware, you can play the whole game from either your hard drive or a USB stick for no money whatsoever. And you should: it was a real milestone, a landmark in PC gaming history.
5. Neptune's Pride
Get it on the official website.
Why it makes the list: This huge 4X strategy game is a little out of the ordinary. Instead of joining your friends for play sessions at the same time, attempting to take over the galaxy in one complete burst, Neptune's Pride is designed to be played over a period of weeks, as everyone battles for control over every star available.
Its exceptionally slow pace encourages careful planning, strategising away from the computer screen, and striking up deals with opposing players outside of the game itself. There are so many options to consider.
That's why Neptune's Pride was our webgame of the year for 2010. For a sense of quite how involved this game is, try reading the diary of our one-month battle with Rock, Paper, Shotgun .
4. Gravity Bone
Grab it from Blendo's website.
Why it makes the list: It's best to know as little as possible about Gravity Bone before you play it, otherwise you'll ruin the precise reason why it's so exceptional.
Know that it's by Brendon Chung, a.k.a. Blendo Games, the guy who went on to create the likes of Flotilla and Atom Zombie Smasher. Know it uses the Quake II engine to create a sort of abstract cartoon world of spies and suave parties. Know it's brilliant.
Don't know what you're asked to do in it. Don't know anything about the story. Don't know how it ends, or which rules it breaks in the process. Do play it, immediately.
3. Quake Live
Sign up on the official website.
Why it makes the list: Here at PC Gamer we'll always big up Id Software's seminal online shooter Quake III Arena in any way we can. And that's especially true when you can play it for absolutely no coins at all.
Arena is certainly ageing now, and has probably been bettered in its field overall. But to this day, no game has managed to match its ludicrous tempo, its sheer sense of kinetic energy, and its masterful map design.
Quake Live is Quake III in a browser. It runs just as smoothly, looks just as good, and is just as much of a tremendous riot as you remember from all those years ago. Essential playing if you have an internet connection and a sensible taste in multiplayer games.
2. Spelunky
Why it makes the list: On the surface, it looks like a simple platformer. You're an explorer, delving deep into a network of caves, trying to avoid the scheming enemies and deadly traps that reside within. So far, so standard - even if its levels are procedurally generated each time you start the game.
But it's only when you start to push at the outer limits of what you think Spelunky can do that you realise quite how remarkable this game is. Derek Yu has created a game that encourages you to be cheeky, and rewards you for breaking the rules every so often. It's also unfathomably tight as a platformer, and while it's brutally difficult, it's a challenge you quickly learn to work with, rather than resent.
The environments change as you plough on through, and there are plenty of secrets to be found. I still haven't completed the bloody thing after two years, as there's no save feature and I'm simply not good enough, but it's still one of my favourite games in the world, free or otherwise.
