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Terror Chasm Development Recap 3: Plant Monster-

At Twisted Jenius, we love our monsters. And one of my personal favorites has always been man-eating plants (due mostly to my obsession with Little Shop of Horrors as a kid). However, with few exceptions this type of creature is usually treated as a side threat, rather than the primary menace, in most media that depicts it. Even in The Day of the Triffids (1962), it could be argued that the global blindness in the movie is a much bigger threat than the titular plant-life itself.

This is why we really like the idea of making a plant the main monster of our game. This also really reinforces, and even epitomizes the idea of PvE (player versus environment) as a game design style, since plants are so often heavily associated with the concept of "environment". Not only are there dangerous traps and platforming chasms that you have to traverse in regards to the temple itself, but there is literally murderous vegetation coming out of the walls to attack you! From a symbolic standpoint, it's very blatantly telling the player that the environment is against them. I'll also mention that another inspiration for using a botanical antagonist in conjunction with the idea of an ancient temple, came from the 2008 horror film The Ruins, though the plants in Terror Chasm are much more active, tearing through the walls to pursue you with the speed and ferocity of a hungry predator.


From a gameplay standpoint the plant monster is designed to create a sense of urgency and limited time. You can't stay in one place for very long without dying and even when you're not jumping over the chasms platforming, you're still never safe. The vines can rip out of the walls or ceiling and come to get you from any direction. Your only choice is to keep moving and the longer you remain in a level, the greater the chance that you will die. This creates a constant feeling of suspense and tension for the player, with ominous music playing as the plant grows nearer. And in addition to this, you can't even fight back. All you can do is run from it and this creates a feeling of helplessness in the player. Terror Chasm is not a power fantasy style of game, and is instead emotionally closer to survival horror in the sense that you are at the mercy of the environment and you must struggle and fight to survive against overwhelming odds. If you push forward too quickly you could easily fall to your death in one of the chasms or get caught in a bone crushing trap, but if you hesitate or stand around too long the plant will get you. Basically, as a gameplay mechanic, the plant monster functions as a device to keep the player moving and keep them on guard constantly by adding another variable that they have to contend with in addition to the puzzle/platforming aspects of gameplay. And from a symbolic and even marketing standpoint, the ferocious vegetation serves as a more distinctive antagonist and icon for the game that is a little bit easier to pin down and solidly depict than more vague ideas about the environment being your enemy. It's a tangible monster.


These botanical predators come in several forms. The most common one in the game right now is the simple vine that whips out to tag and pierce you. The idea is that these vines grow through the walls like a normal jungle vine, but at an accelerated rate and do so consciously, with the deliberate intention of pursuing the player. They rip through the stone walls of the temple like a train barreling after you, and if they catch up, they get you. When they shoot out at the player they don't instantly kill them the first time, but they do inflict damage.

Of course being fans of the classic Venus Fly Trap style man-eating plants, we naturally had to have one of those in Terror Chasm. This is the dreaded Munch Weed. In the current version of the game, which is still in the alpha stage, the Munch Weed acts as a sort of finishing move for the plant. When it decides it is going to stop playing around and finally kill you, it quickly grows out of the wall and snaps around the player's avatar and promptly gobbles them up. While the act of eating the player is not likely to change, it's possible we might expand the Munch Weed's role in later iterations of the game. While death-by-Munch Weed is not the most common way for players to perish in Terror Chasm, we still consider this fiendish flytrap to be the most notable mascot of the game.

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The most challenging part of developing the plant monster for Terror Chasm was designing its navigation A.I. The vines have to be able to chase the player while moving around all of the surfaces of the walls and ceilings. This is more complicated than you might imagine, because it has to be able to navigate a truly three-dimensional space, while simultaneously sticking to certain rules (namely it has to run along the walls perfectly), and on top of that it has to locate, chase down and attack the player (which means it also has to be consistently facing the correct way, while it's doing all of this). This is a bit more challenging than most enemy A.I. navigation that only runs like a human along a two dimensional floor. That type of A.I. navigation only has to worry about moving along 2 axes (X and Y, or if you prefer, front and back and side to side). But the plant's A.I. has to be able to travel the Z axis (up and down) as well, and that creates much more complicated math. The standard navigation A.I. from the Unreal Engine that we're using to develop the game, wasn't able to do what we needed. So we had to program our own custom A.I. system. We even set up a virtual test room within the engine to make sure that the A.I. knew how to properly navigate all sorts of different wall configurations.


In the current version of the game the plant's A.I. only has one chase behavior, where it relentlessly pursues the player. As development progresses, we plan to give the plant monster a wider variety of behaviors and different ways of doing things (for instance, sitting and waiting to ambush a player, or choosing to go after only one specific player once we integrate multiplayer into the game). We also have plans to create even more and different types of plant attacks and different forms the plant can take. By giving the plant A.I. more ways of behaving, this should make this enemy even less predictable and the game even more "interesting" (a.k.a. freaking and disturbing).

- False Prophet