Megastructures.

Big concrete is taking over. There are now enough megastructures in games to justify a whole bundle on Steam. You may not be familiar with the term "megastructure" if you've not yet been cornered by your architecture-obsessed pal in the pub, or by your manga mate who keeps telling you to read Blame. It is basically an artificial space so huge you can't easily conceptualise it. One enormous planet-covering city encased in a shell. An orbital world many thousands of kilometers in circumference. That awful shopping mall in Edmonton, Alberta.

Big weird places that make you feel like an insignificant pipsqueak, essentially. Megastructures are not new to videogames. The subterranean complex of Portal 2 stretched further than fans of the first game would have guessed, and the cavernous corridors of Halo suggest a galaxy of long-lost giants. But now indie developers are increasingly exploring these colossal spaces. And small developers, it turns out, go pretty big.

"I spent quite a lot of time in my childhood staring out at vast roads from nearby hills full of little travelling dots," says Aleksandra Herout, developer of Metal Garden, a first-person shooter set in a drab land with a titanic concrete ceiling for a sky. "As the place I grew up in is a transport hub for the greater region, there was much of this architecture to be found in local landscapes. 

"It wasn't just the size that made them stick with me, but also the sense of anticipation. The promise that this open road would lead me somewhere else. I kept returning to this feeling again and again throughout my life, and it very much impacted the visual language of Metal Garden."

'It is large enough if it makes your head spin and heart pound'

In Herout's 2-3 hour singleplayer shooter, you wander lonely hilltops and lurk through deep blocky catacombs, routinely blasting dark gunfolk and beefy catlads who - it is suggested - have caught wind of a priceless discovery: a way out of the structure. The shotguns and sniper rifles are straightforward, and the jetboot doublejump is as satisfying as equivalent leaps in Destiny 2. But it's the landscape that makes Metal Garden easy to recommend (plus it costs peanuts).