There’s another world, parallel to our own - one made up of hidden or decayed places, built by people but used only by a few or abandoned altogether. We are separated from it by a few metres of concrete when we walk the streets or use a subway; it’s just above or below us in the mechanical floors of hospitals and universities; we can see it in the empty industrial buildings visible from canals or from moving trains. These kinds of spaces are all around us, and yet rarely seen. Some, like steam tunnels, are the blood vessels that keep towns and cities alive. Others, like the ruined factories of Detroit, are the parts of the urban landscape abandoned by people and capital and left to fall apart.

These eerie locales have a grip on the imagination of many people, not least the urban explorers who venture into and photograph them. They also have a powerful hold on fiction, which often imagines a life driven out of the light by some catastrophe and into the dark places, often underground. This trend has been particularly strong in videogames, where the hidden and decaying areas of cities provide a venue for post-apocalyptic struggles. Numerous games have mined this territory, but few have done so as effectively as the 2010 survival first-person shooter Metro 2033.

Hostile Waters has both an unusual premise and unusual gameplay. It is a war game set in an utopian world that has abolished war altogether; and it is a strategy game in which the player is not limited to giving orders, but can actually directly control units on the battlefield. In both its story and its gameplay, Hostile Waters requires players to re-learn war.

 Like  Populous: The Beginning, Hostile Waters was the product of a veteran British games developer entering its final years. The similarities don’t end there - Hostile Waters also failed to receive the recognition it deserved upon release in March 2001 - at least from consumers - and sold poorly. One likely reason is the lack of multiplayer, which was to be added in a patch which never saw release. While not much discussed even today, Hostile Waters has been called “one of the best games you’ve never played”. This minor cult reputation is built on the satisfying combination of those two key elements - the game’s unusual story, and novel gameplay.

By 1998, Bullfrog Productions were one of the most successful, innovative and respected games development studios in the world. With games like Syndicate (1993), Theme Park (1994) and Dungeon Keeper (1997), the British studio had built a reputation for creative and original releases, known for their humour and novel game mechanics. However, dark times lay ahead. The company’s acquisition by Electronic Arts and the departure of co-founder Peter Molyneux to found his own studio would endanger the company. Within a few years numerous projects would be cancelled, and Bullfrog would be gone, absorbed to become just another cog in the EA machine.

Despite these ominous signs, 1998 saw the release of one of Bullfrog’s most important, and sadly underrated games: Populous: The Beginning. The game is a unique hybrid of two distinct gameplay styles: the god game, which Bullfrog had pioneered with the original Populous in 1989; and the real-time strategy, which was then enjoying its first major boom of popularity in the mid- to late-1990s. While The Beginning is primarily an RTS, it draws significantly from the Populous series, to which it serves as a loose prequel. While the earlier games put players in the role of a mighty god overseeing the advancement of a human civilisation, The Beginning has them guide a powerful shaman struggling to achieve godhood. While at the time critics were muted in their response to the game - frankly confused by its radical new gameplay style - Populous: The Beginning is an extraordinary strategy game, easily one of the most unique and engaging ever made.

The late 1990s and early 2000s were a golden era for strategy and management games of all kinds. Whether you wanted to build ancient Rome, fight your own version of World War II, or establish colonies in another star system there was at least one game to suit your purposes appearing on the shelves. One way for developers to compete in this crowded market was to combine and hybridise strategy genres - as British developer Firefly Studios did with their first game, the enduring success Stronghold.

Firefly were well-placed to advance the fusion of city-building and real-time strategy gameplay. Their founders, Simon Bradbury and Eric Ouellette, had both worked for the successful developer Impressions Games, which had been acquired by Sierra in 1995. There, they had worked on the successful Caesar series of city-builders and the medieval strategy series Lords of the Realm. These would each be a strong influence on Stronghold, which was developed in a single rented room in South London and eventually released by Take 2 Interactive in October 2001.

The sudden and unexpected announcement of a new XCOM game provoked a wave of speculation. Fans of the series, which was rebooted to tremendous success by Firaxis in 2012, pored over the trailers. Chimera Squad was variously described as a sequel, a spinoff, a testbed of ideas for a forthcoming XCOM 3, and even as a "glorified DLC".

The wait to find out was not long, however, as the game was released just days later on April 24, 2020. Chimera Squad turned out to be a very interesting prospect indeed. Just as the heroes of this new entry in the series are a mix of human, alien and hybrid members - hence the title - the game itself is a strange mix of familiar and new elements. This remixed formula is mostly successful, and should appeal to a hybrid audience of XCOM veterans and newcomers to the series.

In 1991, the release of Sonic the Hedghog was a watershed moment for Sega's flagship console of the time, the Megadrive (or Genesis, as it is known in North America). The lightning-fast platformer cemented the success of the console, and launched a huge series which continues to this day. By 1996, however, the Megadrive was reaching the end of its lifespan and there was time for just one more Sonic game on the platform before the series moved fully onto its successor, the Sega Saturn.

That game was Sonic 3D Blast, which had versions released for both the Megadrive and the Saturn. The game was actually developed primarily in the UK, by British developer Traveler's Tales, who were given the task by Sega in the days before they were consigned to a hell of their own, developing only countless Lego games. Over the years, 3D Blast has been one of the more divisive games of the series for its unusual isometric perspective and for gameplay which is much slower than the other Sonic games of its era. These aspects have long provoked a mixed reception, but there's a case to be made that Sonic 3D Blast is if not the best Sonic game on the Megadrive, then at least the most playable.

The unexpected and and immense success of Commandos: Behind Enemy Lines meant that the development of a follow-up was an obviously good move. While a sequel would eventually materialise in 2001, the first step for Pyro Studios and publisher Eidos was to design a standalone expansion: 1999's Beyond the Call of Duty.

Introducing eight new missions, superior graphics, more interactive environments, and new skills which slightly balance out the responsibilities of the characters, Beyond the Call of Duty is an excellent expansion set that should be seen as integral to the main game.

The original 1999 Unreal Tournament has been a favourite game of mine since I picked up a copy of its "Game of the Year" edition in Toys 'R' Us for £10 - that is to say, for a very long time. As a kid, I was unaware of the fierce rivalry between fans of UT and Quake III as to which game deserved the deathmatch crown; I'm not sure I've ever played UT online.

For me, it was the single-player that mattered - ironic, given the intense multiplayer focus of the game's design. As with Quake III, the solo portion of UT is not prioritised. A thin plot is used to link together a series of arena battles against AI bots, as one bout of grisly bloodsport follows another.

​Suprisingly, the worldbuilding and background detail in UT, a game essentially without a story, is for me one of its best and most fascinating aspects. With only Unreal to build upon, the game summons up an engaging, half-glimpsed world using only one cutscene, flavour text, and the design of its maps. That this world is never explored properly only serves to make it more tantalising. How can this work?