In designing levels for Research 7, I wanted to achieve the following:
Each level has its own visually stimulating theme
All rooms & environments must have player & in-world purpose
All rooms & environments need to be memorable and unique to help the player navigate successfully
Minimise backtracking
I must include elements of verticality to provide more visual and gameplay variety
I must provide varied challenges that test learned knowledge & skills
Gameplay must stay true to the Alien Swarm formula (varied pacing throughout each level, set pieces, surprise alien appearances, and frantic combat)
As each level needed to be visually stimulating but clearly related to the levels before and after it, I began by thinking about the narrative I was delivering. I was telling the story of alien samples arriving at a secret research lab, so it made sense that the first mission would start in or near a transport hub, the place where the samples arrived. Level 1 became a landing facility, complete with parked space ships, crates of cargo, and dingy hallways that connected one area to the next.
Top left: Level 1 - The Transport Hub; Top right: Level 2 - The Research Facility; Bottom left: Level 3 - The Caves; Bottom right: Level 4 - The Infested Mines
The areas shown in the images above are also good examples of visual landmarks. They provide the player with mental references so they can better understand the level's layout and topography.
I began thinking what each of these levels would look like. Who would inhabit them? What would happen in them? What would the scientists have done on receiving the shipment? How would the aliens behave having taken over the facility? What rooms would be present and how would they be connected? And most importantly, what gameplay did I want to feature in each level and how could I best design areas to suit that gameplay?
I created 2D level sketches that turned into 2D floorplans and layouts, theorising the best places for enemy spawns and encounters. These 2D layouts were then recreated in Hammer, and turned into fully functioning levels.
Top-down minimaps for levels 1-4 (left to right)
Levels are mainly linear with minimal backtracking. Areas alternate between open and closed, heightening and releasing tension, and giving plenty of combat variety.
Diving Deeper - The Security Override
Level 2 features a set piece initiated by players deactivating a security override. In terms of play space, the area in which this takes place is very simple: it’s a straight section of walkway with a wall on one side and a railing on the other. Beyond the railing is a large, dark room with a low floor that the player cannot access.
When the security override is activated, aliens begin pouring into the lower room, starting at the far end and running towards the railing. As they run, lights above turn on in sequence, illuminating the advancing aliens and adding a sense of drama and tension. The aliens momentarily disappear out of sight below the walkway, then climb up over the railing.
I experimented with the width of the walkway to find a size that allowed the player some freedom of movement while simultaneously feeling crowded as aliens poured over. Adding to the sense of rising tension are several boomer bugs that appear the far end of the walkway and stride towards the player. Players need to prioritise the boomer bugs without letting drones get into their midst.
There’s a little bit of design trickery involved in this encounter. The alien instances that climb over the rail aren't the same alien instances you see running across the floor. Instead, alien instances on the floor get destroyed as soon as they're out of sight, then a new instance is spawned that climbs over the rail. This saved me having to script the transition from floor to wall and the transition from wall to rail, streamlining production without sacrificing player experience.
The Fan Puzzle Room
Shortly after the security override section is a simple puzzle set in maintenance area beneath the labs. Players have to activate three switches to force a fan to malfunction. The fan explodes off its spindle, clearing the way for the players to proceed into the forest outside the facility.
I wanted this section to contrast with the frantic security override section players have just faced to provide varied pacing. To do this, I included few enemies. The enemies that are there, however, are some of the deadliest in the game: parasites.
In the original Alien Swarm campaign, these parasites featured only in vents and other damp, cramped areas. The styling of this area, with red lights and rugged metal floors, is intended to remind players of these areas, warning them that parasites are present even before the first one makes its appearance. Parasites are extremely deadly, so I included only one or two (depending on difficulty selected at mission select). The best way to deal with parasites is by spotting them early and keeping your distance, so I made sure the player had room to back away and opportunity to spot parasites from afar.
The design of the puzzle itself is relatively straightforward, with two of the three buttons placed in easy reach of the fan. The third is further away, and requires players to walk through an area with few movement options. By this point the players knows there are parasites present, so the design of this area forces them to look along the hallway to spot danger early because they won't have the opportunity to dodge.
The Shield Bug Bridge
The final section I’d like to cover is the design of an encounter in level 3 involving a shield bug and a narrow walkway. Shortly after the player enters a cave, they find themselves walking over a rocky bridge with no sides and a steep drop off either side. Halfway across this walkway, they encounter a massive shield bug. These are aliens that can only be damaged from the back, and they have attacks that knock players away; both difficult things to handle on a narrow bridge.
As with the security override example, the width of the bridge was extremely important to get right. It needed to be wide enough that players wouldn’t get knocked off every time or feel as though they’d been treated unfairly, but narrow enough to provide a challenge. Through testing I found a width that seemed to work for the majority of players, but I needed to include another option for those more cautious players, and for those struggling. I added a shelf below the beginning of the bridge, creating an area where players could land safely if they got knocked off. This way, the bridge challenge suited both gung-ho, guns-blazing types and more cautious players.
The depth of this cave was also important to get right, not just because the fall needed to be a clear threat to the player, but because of the alien eggs I’d placed at the bottom. The destruction of alien eggs is often an objective in Alien Swarm, but that wasn’t to be the case here; they were purely for decoration. I therefore needed to place the eggs high enough that it was clear what they were, but low enough that players wouldn’t think they were an objective that could be completed then and there.
A Note on Difficulty
Difficulty can be set at the beginning of each mission, and as well as increasing the amount of damage each alien does, it alters numbers of aliens and where they spawn. I tailored the position of alien spawners and the number of enemies each spawns to suit each difficulty level. At the higher difficulty levels, I also mixed additional enemy types into some encounters, providing fresh challenge for people who had just graduated from the previous difficulty level.
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