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Building replayability into the intricate architecture of Tokyo 42

The gameplay loop in this open, isometric world will be familiar to GTA fans. Free-roam to figure out escape routes and sightlines to use later, find hidden unlockables, or simply enjoy the scenery.

Chris Priestman, Blogger

June 6, 2017

11 Min Read

In the opening minutes of Tokyo 42, you’re accused of murder and have to flee your cramped flat with a stampede of bullets hot on your tail. Before long, you find yourself hustling to survive in the cloud-piercing heights of its futuristic city. You get to know a network of criminals, who help you chase down a way to clear your name, which ironically leads you to actually commit crimes, and lots of them. 

The gameplay loop found in this open, isometric world will be familiar to anyone who has played Grand Theft Auto. You can free-roam to figure out escape routes and sightlines to use later, find hidden unlockables, or simply enjoy scenes of flying cars set against colorful tower blocks.

When it’s time to get down to business, you accept a mission, trading dangerous favors for weapons and cash. As well as the expected gang shootouts, there are assassination missions, parkour challenges, and the occasional stealth operation. 

There's plenty to do in Tokyo 42, not just in terms of upping the numbers - missions completed, items collected - but more commendably in how it's so open to playful experimentation. The two-man team behind it have spent their time trying to design a city that fosters player expression.

Whether that's in providing a choice of weapons, architecture that asks to be traversed in unconventional ways, or AI crowds that fluctuate between predictability and surprise. It's a game that invites replays simply to toy with its systems, for new combinations of its systems often reveal new ways to beat each goal, some of them not even anticipated by its creators. Their journey to get the game to this state has been a lesson in how to find balance amid disorder.

Unexpected origins

For the most part, Tokyo 42 prefers not to tell you how to play - it wants you to experiment with its missions, to try out different routes, tactics, and weapons. It’s in giving you this liberty that the game earns its replay value. When you finish Tokyo 42, you unlock a terminal that lets you access all the story missions you’ve completed, so you can try out other ways to beat them. It’s a feature that proves developer SMAC Games understands the lasting appeal of the game it’s made.

But here’s the surprising part: Tokyo 42 wasn’t even conceived as a single-player game. It started out life as a demo for a multiplayer deathmatch level. “I feel like that demo we came out with was pretty well polished and gave a pretty good impression of what the game would feel like,” says Maciek Strychalski, the art half of SMAC Games.

“I think we would have probably run with that multiplayer set up with a few extra levels if we hadn’t met Mode 7 at this game dev event called Interface. I think the polish made a good impression at the event, and we basically walked away with a publishing deal.”

Mode 7 is the developer of turn-based strategy game Frozen Synapse, the football spin-off Frozen Cortex, and is currently working on Frozen Synapse 2. The team, while small, has pedigree when it comes to visually striking and highly-replayable tactics games. Tokyo 42 is its first venture into publishing, but that didn’t sway Strychalski, who says “it felt like they would best understand what we would need to get it done.”

Do it your own way

One of the first agreements between developer and publisher was that the multiplayer demo would need a single player mode to accompany it. The reason was simple: “we couldn’t guarantee a healthy multiplayer community in an unreleased game,” says Strychalski.

The multiplayer idea they had to work with saw players hiding from each other amid the city’s scenery, blending with crowds to move between cover, and then jumping out to get the kill - a bit like an isometric version of Spy Party

The stealth part, the gunplay, and a feline companion called Trackacat which detects hidden enemies, was all there from the start. With that as a basis, Strychalski worked alongside Sean Wright, the coding half of SMAC Games, to give Tokyo 42 an open world for players to roam. 

“Since we wanted to make an open world single player, it became obvious to us that the game lent itself to the multiple approach style of play that you find in the latest Metal Gear Solid,” says Wright. “The idea from our side was to set up the mechanics in such a way that various approaches would achieve your goal equally well in any generic mission setup.”

A typical mission in Tokyo 42 has you enter a restricted area, which is full of patrolling armed guards, and take out a target at the top of a building. You could run in there, guns blazing, dodging bullets as if you were playing a shoot-’em-up - the slow-moving projectiles can make it feel like a twin-stick shooter.

You could play it as a cover shooter, crouching behind low walls and using varying terrain height to your advantage. You could climb to the top of a nearby building and shoot the target from afar. You could sneak past the guards, either taking them out along the way or leaving them alive. You could lure a rival gang in from the other side of the city and have the two sides do battle. These are only the most obvious approaches - there are many more to explore.

Ramshackle city

As the pair of developers were trying to balance lots of moving parts, there wasn’t much time for level design and testing, and so spontaneity played a role in that department. Either Strychalski or Wright would have an idea for a set piece and so they’d construct the architecture around that. It might be a building with an obvious side path to sneak down, or a high point built for sniping - but sometimes the way the spaces correlated opened up new, unexpected opportunities.

“The fun part about this is that we allowed certain spaces to interact with others so gameplay paths would often appear unexpectedly at a later stage once some new content would come in,” says Strychalski. “For instance, I’m always searching for a new sniper perch to clear the way on some of the enemy-dense levels.”

Here, you can start to see how Strychalski and Wright would build an area and then play around in it to see what was the most fun thing was to do there. Their discoveries sometimes changed the game itself - finding out how fun the game was as a bullet-hell shooter had them open up some spaces - as well as helped them to design the missions.

It’s a process that involves being playful and open to ideas rather than careful planning and precise execution - mistakes were sometimes made, but they couldn’t go back on them, “instead opting to use those mistakes and move forward,” says Wright.

Power of the people

While the pair usually had a vague idea of what could be done in a space while building it, it was only when they started testing AI and pathing that structure would emerge. “It’s the AI that brings the game to life, and as much as we discovered things with the city design, the AI would constantly surprise us with what they would do,” says Strychalski. 

“So, for instance, we might lay out a mission with the intention to funnel aggroed enemies through a choke point, but instead they would run to some obscure cover zone far away and start sniping and throwing long-range grenades. Those sort of things would later be integrated into the mission (if the AI agreed, that is).”

The AI is what excites Wright the most. When he first started getting into game development with Unity, he was struck by its component-based model, and adopted it to develop the AI for Tokyo 42. “Each enemy AI will have at any one time up to about 10 script components on it - one for pathing, one for ballistics, one for cover, one for emotions, etc,” Wright explains. “Depending on the agent’s circumstances, the scenario is interpreted by all of these discrete scripts and depending on a dynamic weighting of priorities some update ticks each will take prevalence over others.”

“The script has a host of configuration variables too - for example the cover script has values for the allowed height offset to filter nearby cover zones to choose from, as well as a radius within which to search for cover. These are either standardized, set depending on a specific situation, or randomized within an acceptable degree of uncertainty.”

Keeping hold of that uncertainty became very important to Tokyo 42 as it allows for diverse behavior in the enemies. Even now, Wright sometimes finds himself questioning how an AI enemy figured out a certain tactic or maneuver. “I like where it’s at and see it as a sort of harnessed chaos,” he says. It’s an apt way to describe how the entire game is held together.

Under control

You can’t expect every player to get to grips with “harnessed chaos,” though, and so what SMAC did was to add tutorial missions to the start of the game. They’re kept simple, and unlike other missions in the game, they tell the player exactly how they should approach them. One introduces sniping, another crowd blending to lose heat, a third has you sneak up on your target with a katana. 

“The first few missions are mostly there to introduce the common controls of the game,” says Strychalski. “Also just so players know these features exist because Tokyo 42 has quite a rich control scheme and there’s a couple of things that are really needed in tougher fights. For instance the way we’ve implemented grenades, whilst rad, uses a new design pattern which players have to get used to.”

After that, the only way that SMAC tries to influence playstyle - apart from level design - is with small challenges in some of the missions. These might be to take the target out with a melee weapon or to complete the mission without being spotted by the enemy. “We realized that some of the missions can be easily powered through or stealthed through whilst the alternate path is trickier,” says Strychalski. “This variance changes from mission to mission. So we really wanted some mechanism that would ask players to try out some of things we’d designed in.”

He adds that he sees those extra challenges as a way to please players who want to max out what Tokyo 42 has to offer. Some of the challenges are made particularly tricky with those dedicated players in mind so that they have interesting challenges to pursue once the game is over.

Every window an opportunity

Outside of the missions, SMAC has added other small touches to tempt players to extend their stay with the game’s single player. One of those is the Nemesis system. Once you’ve angered one of the game’s gangs, they’re likely to send an assassin after you, and the brilliant part is that you don’t know who or where they are. “You’ll hear the tell-tale gong of a Nemesis spawning and suddenly you’ll start inspecting the crowds around you for suspicious behavior - much like the multiplayer,” says Strychalski.

There are also lots of secrets hidden in the environments in Tokyo 42 for you to hunt down. Many of them are weapon and cosmetic unlocks, signified by a spinning symbol, just out of reach. You can spend a lot of time trying to work out how to reach them.

Another type of secret is influenced by the Where’s Waldo? checklists that give you certain sights to hunt down in each scene. “There are a bunch of tiny things happening out there in windows and hidden around,” says Wright. “For instance, there’s a dude in some apartment having a crazy Frozen Synapse session.”

Of course, if and when the single player of Tokyo 42 does run its course, then you can jump into the multiplayer mode. SMAC has some plans for that in the future, too. “We have been discussing some other modes that further make use of what we learned [during development] and made for the single player,” says Strychalski. “So we’ll see if we can somehow get these modes in.”

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