The invisible wall has long served as a disappointing reminder to curious and adventurous gamers that the worlds they enjoy exploring have a limit. For developers, they serve as barriers created to prevent players from moving outside of the intended play space and discovering the malformed, untextured geometry beyond. But whether you're a player or developer, invisible walls are necessary, for no game is capable of rendering an infinite world that's also full of infinitely interesting things to see and do. Even the randomly-generated terrain in Minecraft comes to an end after 32,000,000 metres.
Not every developer is ready to settle for such arbitrary restrictions as invisible walls, however. Some go out of their way to bring this barrier back into the context of the game world and make it part of the experience. Here, then, are the top 10 invisible walls, creatively reimagined for sandbox levels or open world games.
10. The Elder Scrolls Online
Zenimax Online Studios, 2014
Swarm of Piranhas
Travelling to far off places and exploring the unexplored has been one thing The Elder Scrolls series consistently encourages its players to do. There is something sublime about seeing a mountain in the distance and knowing that you can actually climb to its peak.
But Tamriel does have its limits. Whilst Oblivion and Skyrim took to simply displaying an on-screen message telling you that you could travel no further, The Elder Scrolls Online takes a slightly snappier approach--in that you'll be devoured by a swarm of snapping, ravenous piranhas if you swim too far off the map. It's a nasty end, but at least you can easily ressurect back on land with naught but a few hundred bite marks in your undergarments.
Piranha Bytes, 2001
Going from biting piranhas to Piranha Bytes--the German developer of the Gothic series--we find ourselves in Europe's unforgiving alternative to The Elder Scrolls series. The Gothic games have typically offered fewer gorgeous vistas to gaze upon than Bethesda's open worlds, but more metaphorical boots to be crushed under.
This is most true of the first Gothic. Set entirely within an island prison colony, in which the prisoners themselves have taken over the land and formed competing factions, Gothic kept players contained in its world by surrounding it with a giant, dome-shaped electric force field. If players ventured beyond it, they'd find themselves crackling with blue lightning and then immediately zapped to death. The force field was a part of the story itself, which explains its use as a magical barrier erected to keep the prisoners contained. We tried to go all Katniss Everdeen on the barrier, but our pathetic wooden arrows didn't make for great eletric conductors.
8. Far Cry 2
Ubisoft Montreal, 2008
Sudden Malaria Attack
Far Cry 2 is one of the few first-person shooters that beats you down at every opportunity, and Ubisoft Montreal's approach to keeping players contained within 30 mile square (50km2) slice of the savannah follows suit. The same malaria infection that blurs your screen and causes you to find somewhere to hide and scoff a pill also keeps you from wandering too far off the beaten track. You'll collapse, black out, and reappear a few seconds later back within Africa's boundaries. If you were driving a car, that'll be gone forever--because Far Cry 2 giveth, and Far Cry 2 taketh away.
7. World of Warcraft
Guardian of Blizzard Encounter
World of Warcraft entices players to explore with promises of colourful new environments and strange creatures to farm for experience points. The most curious players can sometimes explore too far, and catch a peek behind the curtain to see content Blizzard isn't yet ready to reveal. To ward off intrepid explorers, the developer created the Guardian of Blizzard, a powerful enemy that one-hit-kills players when they venture into unfinished environments.
The Guardian was retired when a new, less-exciting mechanic that teleported players back into the world was adopted, but they can still be spawned and controlled by Game Masters who wish to instill a little fear into Azeroth's heroes.
6. Grand Theft Auto IV
Instant Six Star Wanted Level
Grand Theft Auto V offered incredible freedom to explore by opening its entire world to players from the game's outset. That wasn't the case in Grand Theft Auto IV. Liberty City was divided into islands, separated by bridges that could not be crossed until specific points in the story. But there's always usually another way around in an open world, and in the case of GTA 4, the ability to swim without drowning made its return from Grand Theft Auto: San Andreas. However, if you tried to swim under the bridge and across to the other island, you'd be slapped with an instant six star wanted level. Cunning drivers could also find ways to flip their cars over the barricade, leading to a good old fashioned police chase--but there's something delightfully absurd about making the entire island shut down because you went for a dip, and had to be brought to justice.
5. Unreal Tournament 2004
Vaporised by Ion Cannon
With Unreal Tournament 2004 introducing bigger maps, along with land and air vehicles to traverse them, Epic needed a new way to keep players inside its futuristic arenas. For the locales not enclosed by walls or sheer cliffs, the developer opted to repurpose Unreal Tournament 2003's superweapon, the Ion Painter, into an omnipresent Ion Cannon.
Travelling too far from the action caused a message to pop up on your screen, warning you that were being locked on to by one such cannon. After a countdown timer, a bright pink blast of energy falls from the heavens and incinerates your body, leaving only a charred skeleton to ragdoll its way back into the arena. If you're skilled enough in a Manta hovercraft, however, the Ion Cannon blast can be dodged.
4. Serious Sam 3: BFE
Devoured by Giant Sand Worm
Serious Sam's explosive debut took the first-person shooter outdoors to some of the most expansive arenas ever seen, and with the ridiculous on-screen enemy counts to fill them. The third entry in the series, a prequel, shifts those open firefights to an apocalyptic Earth ravaged by alien forces.
Where the previous entries in the series boxed Sam into those arenas with high cliffs or walls, Serious Sam 3: BFE took a more interesting approach. Venturing out of bounds would cause a giant, Dune-like sandworm to burst upward from the dirt and devour Sam whole. Unlike every other enemy in BFE, these sandworms could not be killed, even when pummelled with a Serious Cannon.
3. Just Cause 2
Avalanche Studios, 2010
Road to Nowhere
As we head into the final three contenders on this list, we must take a slight deviation by means of Just Cause 2. Heading to a certain boundary in the islands of Panau reveals just why developers need to create ways to box players in, because here you can find the complete lack of a boundary. The world simply ends, with land geometry being perfectly sliced off at a certain point, and nothing but water stretches beyond. Hilariously, the game's pedestrian AI doesn't realise this, and cars travelling along this road that leads to nowhere will drive off the edge of the world, without a care in the world.
2. Motocross Madness
Rainbow Studios, 1998
Invisible Bike Cannon
The original Motocross Madness was something of an open-world dirt bike stunt game. It offered huge, open levels rippling with undulating hills and valleys pull off a sweet can can. Surrounding these stunt quarries were huge cliffs which, thanks to the funky physics of the time, could be scaled by riding up them completely vertically. But the developer knew players would find a way up here, and so, after riding a further couple of meters, the game would suddenly launch the bike and rider high into the sky and back in the direction of the level. Talk about getting some sick air.
Shark, Battleship and Killswitch Triple Threat
Crysis takes the top spot on this list for implementing what is probably the only three-stage system designed to keep players within a game world. Let's break it down. First up, if you decide to swim off the white sands and out into the pristine tropical waters, you'll eventually encounter a lone shark. This guy menacingly circles you a couple of times, then chomps down for an instant kill. However, these sharks can be killed, or bypassed in a boat.
Getting further past them will cause the North Korean battleships dotting the horizon to fire an instant-kill torpedo directly at you. But, with some skilled driving, these can be dodged. Make it past those torpedoes, and your commanding officer will freak out and hit your Nanosuit's killswitch. That's right - your suit has a killswitch. Super strength and super speed don't feel so powerful anymore.