Every gamer can think of at least one title that they never got round to playing, whether it was because the mere presence of the disc would have melted their underpowered PC, their pocket money didn't stretch that far at the time or there were simply not enough hours in the day.

Unlike music and films, games have never had much of a shelf life. They appear at full price, they reappear on a bargain label and then they're gone – lost in the mists of time. Well, almost. The internet provides the perfect opportunity to bring classic titles back, either commercially through online stores that don't need to worry about shelf space or via enthusiast projects. It's an opportunity that many are exploiting.

Good old games

Two companies in particular are leading the way: Good Old Games (GOG) and Valve. The former runs www.gog.com, where you can pick up games for between $6 and $10. The latter is in charge of Steam. Although the site mostly focuses on newer games, it also offers publishers the perfect chance to squeeze a little extra out of their back catalogues. Ubisoft, Rockstar, EIDOS and Activision are just four of the major players who are involved.

If you pirated Doom back in the day – and if you were around in the day, odds are good that you did – consider this the perfect time to atone. Steam is good, but it's GOG that really impresses. Instead of simply selling games like any other product, it focuses on providing a good experience.

Most of the games it offers have been floating around the pirate sites for years, begging the question of why you'd bother paying at all – but there's a simple answer to this query. Buying from GOG gets you the game, with all the hard work involved in getting it running already done for you (typically via a piece of software called DOSBox).

There's no DRM, no serial numbers and you can re-download a game as often as you like. In addition, each game comes with a number of extras ranging from simple avatars to full PDF manuals, wallpapers and complete soundtracks ready to be put onto your MP3 player and taken on the go.

Not all the games on offer are classics – Waxworks, Simon the Sorcerer 3D and Messiah in particular could quite easily be dropkicked out of history without a single tear – but many are worth a second look. Freespace 2, Fallout, Jagged Alliance 2 – these are classics by anyone's definition.

Rose-tinted glasses

Going back to a much-loved game can be a sobering experience. Time is rarely kind. We remember the highs of beating a game like X-Com (UFO: Enemy Unknown, to be more accurate) but rarely the clumsy interfaces or blocky graphics.

The cut-off point tends to be different depending on the genre. The more technologically advanced the game was in its day, the less likely it is to stand up nowadays. Sprite-based adventures like Monkey Island 2 and Sam and Max can still inspire those feelings of old because ultimately they were advanced enough to be able to use proper hand drawn graphics, punchy music and play like pieces of art.

An early 3D FPS, with characters nodding at each other – unable to move their lips as they 'talk' – before stepping into a world of five monsters and guns that look more like bludgeoning devices than sleek futuristic weaponry... well, that's a different story.

However, this sort of thing isn't necessarily a gamekiller. Graphics aren't everything, and when you step into the archives, you know what you're getting into. Good games will usually win out. That's the theory, at least. In practice, it's easy to forget how far we've come in just a few short years.

It's easy to think that real-time strategy gaming AI hasn't improved since Dune 2 until you go back and play Dune 2 in all its faded glory. Likewise, the interfaces and control systems of even today's worst games are nothing short of revolutionary. Tastes change over time, and lessons are learned. No modern game worth mentioning is going to let you render it unwinnable by accident, while the classic adventures were so focused on player choice that they'd happily let you eat an important item only to reveal that you need it to complete the game several hours later.

Some games were nothing short of psychopathic in this regard. Take the first Space Quest game. At one point, you need to sell your character's hoverspeeder to a shifty gentleman on a Tatooine-style planet. If you sell it immediately, you can't win the game. If you refuse to sell too many times, you can't win the game. Only by trial and bloody error are you going to find that if you refuse his first offer, he sweetens the deal by throwing in a jetpack – a jetpack that you need to get to the last area of the game. This isn't an exceptional case, either; this was standard in almost every non-LucasArts game at the time.

Top of my personal hit list was Search For The King, where the only way to finish the game was – several hours earlier – to have spontaneously kissed a gypsy fortune teller to make her teleport away in shock (probably to get a restraining order), followed by petting the lizard on her desk to receive a 'Resurrection Card' that saved you from being trampled to death in the final puzzle. So many years on, the anger still burns.

The advantage of all this is that when you do find a game that endures the test of time, it's that much better. In many cases, you're seeing a genre at its peak, either because a particular game was simply that good (Super Mario World remains the pinnacle of 2D sidescrolling platform games) or because the industry moved on.

Doom still gives a cooperative gaming experience that's a lot of fun thanks to the industry moving towards deathmatch and team-based games instead of letting friends team up together against impossible odds.