Gran Turismo 2
It's hard to remember how big an impact Gran Turismo had when it arrived in 1998. Before GT, racing games mostly featured abstract handling models and either make-believe cars or a small selection of production models. After GT, we came to expect more realistic handling, a huge line-up of real cars and gorgeous replays that - if you squinted - looked like they might have come straight from the TV. GT2 added even more cars, off-road racing and brilliant courses like the real-life Laguna Seca or the tracks based in Rome, not to mention a dedicated arcade mode (which actually came on a second CD-ROM). Neither GT or GT2 is available to download, but the Gran Turismo series continues with GT5 Prologue in less than a week's time.
Castlevania: Symphony of the Night
Despite its 3D prowess, one of the finest games on the PlayStation was a 2D action/adventure - Castlevania: Symphony of the Night. This was the title that reinvented Konami's vampire-slaying series by replacing the old scrolling hack-and-slash combat with a more free-roaming platform adventure game based heavily on Nintendo's Metroid series. Distinguished by superb character design and a cracking score, it's one of the all-time great 2D games on any system. Annoyingly, a PS3/PSP version is available to download from the PSN Store in the US but not over here, which means European gamers will have to resort to the (superior) version bundled in Castlevania: The Dracula X Chronicles on PSP or the fine version available on Xbox Live Arcade.
Metal Gear Solid
Why is Metal Gear Solid so important? Let's just run through some of the reasons. It practically invented the stealth/tactical espionage genre (though Thief: The Dark Project deserves some of the credit there as well). It showed game-makers how cinematic techniques could be applied to action games. It introduced many of us to one of gaming's greatest heroes and some of the best boss characters the world has ever seen. It featured an intriguing plot and showed a kind of self-aware intelligence that few games seem capable of, even today. Visually, it's one of the best games on the system. Gamers with a Wii can enjoy the excellent Gamecube remake, The Twin Snakes, and the Windows version can still be found second-hand. Otherwise, the only way to play the original MGS (legally, at least) is to buy the forthcoming Metal Gear Solid: The Essential Collection, which contains the PlayStation original plus the PS2's MGS2 and MGS3.