Into the 4th Dimension

by Kyzrati on 20130223 , under

As we're all aware, atmosphere is an integral part of the X-COM experience, and an important element for building that atmosphere is sound. The sound of unfriendly footsteps echoing through the darkness; civilians screaming as the aliens find them before your squad does; hearing gunfire pierce the silence as unseen aliens fire on your position, but miss their mark so you still have no idea where they are. These add to the suspense, while also making the "hidden movement" phase that much more interesting (and informative).

This aspect of the game has been on the back burner for quite some time while we squared away the core mechanics, and with that done it's now time to decide what needs to be heard.

  • Weapon fire / attacks
  • Projectile impacts (projectile+material-dependent)
  • Explosions 
  • Throwing/landing (latter could be material-relative)
  • Dropping (essentially same as landing)
  • Picking up
  • Melee swings / misses
  • (Ammo loading/unloading probably unnecessary for now since only possible through inventory window, which has its own sounds)
  • Footsteps (usually terrain-based, but units may override that in special cases, such as flight or huge stompy aliens)
  • Death
  • Footsteps (us. material-based)
  • Door open/close
  • Destruction (us. material-based)
  • Falling prop impacts (unbroken, us. material-based)

Aside from the lists above, the sound system is already accessible through special abilities scripting, so sounds can be connected to just about any game element to create unique situational sounds like a terror unit roaring on spotting a target, or a chryssalid screaming on injecting a victim, etc.

Much of the functionality already exists, as particles and anything that uses them (attacks, explosions, throwing, melee...) are already capable of playing and controlling sounds (which is how the UI emits sound). We still need control for sounds related to non-particle objects, and to [elegantly] deal with various issues like the extreme cacophony that would result from huge explosions destroying wide areas of terrain, footsteps out of sight (it will slow down turns to always have NPC unit steps heard--not sure by how much), and many more I no doubt have yet discover.

After that it's mostly a question of putting together the assets, but I won't be doing all that now, just a core set used for testing/R9.

Fortunately I have handy a nice library of 157 footstep sounds I put together for an old game, so hopefully they'll work well for X@COM without too many adjustments (although I may have to edit them all--doh--to get them to work with the faster movement speed than the game they came from). Categories include dirt, grass, gravel, metal, mud, puddles, water, wood, rocky, snow, stone, and undergrowth. Because you need something other than my wall of text to look at, here's a color-inverted shot of one of the snow footsteps in Audacity (my primary sound editing tool):
Another issue at hand is to determine what level of control the player needs over sound. Besides the obvious option of muting the game entirely, will it be sufficient to split sound effect control into two categories, UI and game? That's what the plan is, in any case.

Other features under consideration (any opinions?):
  • Dynamic sound effect volume based on the distance of the source from the nearest unit under the player's control
  • Music isn't appropriate, but some kind of ambient drone or beat as heard in X-COM can help set the mood (as long as it's not too intrusive).
  • [Unlikely:] Very subdued map-wide ambient/background sound effects, like distant shouts and screams in a densely populated urban map, wind through the trees in forests, etc.
  • [Unlikely:] Environment sounds emitted by props, and heard only by the currently selected unit; examples would include fireplaces, gushing streams, machinery, alien facilities, etc.
  • Radio chatter?

I'm not going to press forward on all this immediately. First there are a few little items sitting on the to-do list that need cleared away while awaiting any comments/input you guys have to offer.
8 comments more...


  • Anonymous

    It's nice to have sounds, even if i'd prefer more gameplay evolution (geoscape, buildings, researchs...). Thanks for making this game ! What about the dark cloud pushing you away from X@COM ?

  • Anonymous

    I think there are 3 categories of sound. UI, game and ambient (point 3 and 4 of that list) with the music being the 4th.

    The first two are essential, the other are nice to have. But if i had to choose between the remaining ones i'd take point 4 of the list as the most important of these 3, as it adds a lot to the atmosphere being able to hear some waterdrops falling in a cave or the buzz of the powersource or the beeps of the navigation in those UFOs.

    Music, as nice as it might be, is the least one in my opinion as you could simply use your MP3-player to get whatever music you want while playing.

  • Kyzrati

    @A1: Said cloud is not "pushing me away" per se, just threatening to put a sudden hold on the project. It could be a good ways out (like many months), so I'll just keep chugging along and make an announcement if/when the time comes.

    I want to work on more gameplay, too, but at this stage in development we need to round out the unfinished sound system before continuing.

    @A2: That sounds about right. In any case, the system will be expandable as each individual sound is assigned a type/category through the text files; it's just a matter of including enough on/off switches and volume controls for each available category.

    As mentioned in the post, while environmental sound effects are great for atmosphere, I wonder if the high frequency of switching control between units would simply make that an annoying feature. I've done it with a single-PC roguelike before and it truly is a nice effect that provides a much more immersive context, but if you're always switching between units, those sounds would continue to change as well, since we can't very well have the sounds for all objects near all of your units playing at once. The effect would be less than symphonic... what do you and others think about that?

    Music ("music") is last on my list as well, and easy to add later so I won't be considering it at this point. I find the background music/ambience from the original pretty nostalgic and well done, but I will focus on using sound only.

    @A3: I have reloading on my original list of sounds, but since that action is only accessible from the inventory menu, the current UI interaction/animation sounds would cover it up so I was considering leaving it out. I agree it's a great sound... Back when I did the inventory menu there were no action sounds, so maybe I'll disable the UI sound for inventory interaction and apply other sounds instead?

  • Carnets Virtuels

    For ambiant sounds, maybe a fade-in system : when you select a toon, there is no sound for two seconds, then the ambiant comes little by little. So if you switch toon ften or quickly, it's not annoying, while if you keep the selected toon, you can enjoy the ambiant sounds. That, and some generic ambiant sounds always on, whatever the toon you have, just depending of the kind of map (factory, town, laboratory, open land...).

  • Anonymous

    Global sounds are a tricky thing. If you are in an open map with a lot of wind in the trees and you enter the only house there that sound should at least being muted.

    But how should that be done? So either local ambient sounds have a trait that mutes the global one, or the global one isn't global but connected to certain cells and the room above them, that contains no other cell.

  • Andrew Sundberg

    I honestly think that music should be a high priority. It's easy and adds a lot to the ambience; the hellish background drone of UFO (and the damn TFTD music with that low drone and then high screech; it gets me every time ;p) is the perfect example. I'm not so much on the ambient sound boat, although global sounds fading with distance from XCom units would be a nice touch.

  • Kyzrati

    @Carnets: Fading sounds like a good solution to mitigate the potential annoyance factor. I will not be including ambient sounds initially, and we'll see how the overall experience will benefit once we have all the confirmed audio features in place.

    @Anonymous: Global sounds that cover much larger regions, if added, would use a system that I've used before on a previous game: maps will be subdivided into "locales" through the map editor, and ambient sounds can be attached to a locale so that as a unit enters/exits a locale those sounds fade in/out for them. (So essentially what you are saying--there would not likely be any truly global sounds.)

    Locales will be useful in other ways as well. They can be named, and it's always nice to have that extra detail/information about where a unit is on the HUD ("Gas Station", "Convenience Store", etc.), or perhaps a record of where exactly they died on your memorial screen, e.g. "KIA: Gunned down by a sectoid soldier in a farmhouse in Bulgaria."

    @Andrew: Yep, music is certainly easy so feature-wise it's not a problem to support it. I don't know if it will fit thematically with the atmosphere I'm trying to create, but 1) that can be determined later, and 2) we'll definitely at least support music since mods may want to make use of it.

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