What "multi-perspective shooter" means, in simple terms, is that the protagonist isn't on the battlefield. Rather, you play a higher-up at the Signal Ops outfit, nestled safely in the comfort of the headquarters, ordering your troops around via scattered monitors.
In this way, the game has a hugely tactical feel to it, rather than that of a regular first-person shooter. On one monitor you might be shifting the spy around, placing radios in designated spots, while a screen just to the right, a lockpicker is hiding in the shadows, so as to stay out of trouble with the local law enforcement.
"The original idea for the multi-monitor interface came while we were all still employed, and dreaming of striking out on our own," explains Josh Enes, co-founder of Signal Ops studio Space Bullet (Jakub Czeszejko-Sochacki and Alex Gorshkov being the other co-founders).
"Our concept artist Alex did a mockup of the multi-monitor interface and sold us on the idea of pursuing the concept to see if it would work out," he says. "We weren't actually sure right away if what you saw on the monitors would be first-person or fixed cameras."
The Commandos series was a notable reference to the Space Bullet team, especially its split-screen interface and tense mission-based action, while the idea of having a home-base area that seamlessly blends missions together is the sort of element you might see in Deus Ex.
Showing multiple simultaneous viewpoints is tricky
Indie development can be tricky enough without having to worry about throwing multiple interactive viewpoints onto the screen at the same time. As Enes explains, there were numerous moments when the team was brought back down to earth of its grand plans.
"On the design side, we had originally thought there would be up to nine monitors," he notes, admitting, "This was quickly identified as being too unwieldy, and also too difficult to see what was happening on each monitor."
And then there was the issue of giving "free will" to those characters who you aren't currently ordering around. Do you allow them to run around in scripted sequences like AI teammates, or keep a tighter grip on the action?
Scripted sequences were "completely the opposite direction of what we wanted for Signal Ops," says Enes. "The end result is the AI will only return fire if they are being attacked directly. As a compromise we allow you to set up agents in a defensive stance to shoot at any enemies that come into view."
Interestingly, the team also came to realize that because the monitors you're looking at are only a small part of your whole monitor, enemies would feel like they were further away from your soldiers as a result of the viewpoint. For this reason, tweaks to the player's vision were required until it "felt right," as opposed to what was realistic.
The HUD also needed plenty of revamps. "Once all the necessary indicators were added, we found that it was an eyesore and covered too much of the agent's view," notes Enes. "We overhauled it to move most of the HUD elements off of the screen and into the frame of the monitor which was, until then, wasted screen space."
From a technical point of view, implementing simultaneous views was a nightmare, putting huge strains on the running of the game.
"Because you could have your agents spread out around the level, we need to keep the whole level simulating physics, AI and all, all the time," Enes says. "It also put strict requirements on how we build the art for the game, making it necessary to compile all the textures into a huge texture sheet. As a result, we had to upgrade our level exporter to automatically slice up the geometry to be able to do texture tiling."
And AI path-finding was quite the hassle too, thanks to the complex environments, physics-based ladders, windows you can climb through, and other such elements.
"Even now we're still tweaking the pathfinding system to weed out the last few conditions where characters will get caught up on something," Enes tells us. "Sole programmer Josh had experience building things like tools and exporters, but programming every system of a whole game was a learning experience. A lot of the original code ended up being rewritten - for example the AI system which was written from scratch three times using lessons learned from the previous versions."
Notably, with the inclusion of a co-op mode the team created a whole new set of challenges for itself. Whereas a single player needs to divide their attention between multiple agents, co-op with friends has the opposite effect, as players must co-ordinate between themselves.