Maelstrom - Developer Diary #3 Feature

In the latest development diary from KDV Games, Elena Khudenko takes a look at some of the technology powering the studio's sci-fi RTS, Maelstrom.

The technology behind the game - Vista Game Engine

We spent the first year of the project planning the technical road map for Maelstrom, and then implementing the framework, which we used to begin building the rest of the game around. At this stage game design and art were still very fluid, but the technology was up and running relatively early in the form of a playable prototype so we could test the games main features and begin tweaking the game mechanics.

We call the technology behind Maelstrom the 'Vista Game Engine', it's our own engine, developed by KDV games, and in many ways works very differently to most game engines you'll see other projects based on. Ideologically it is based on the 10 years of experience that our team collected working on the previous projects, such as Perimeter and Vangers. So, the implementation of all key features as part of Vista Game Engine was really the first stage of Maelstrom development.

Thanks to the unique way it works, our efforts resulted in an engine that's capable of cutting-edge visuals and unique gameplay. Our goal was to create an interactive and destructible environment for the game, and we've realised it in a number of ways.

First of all, there is the terraforming feature - we've elaborated the idea of changeable landscape and given more options. If you've played Perimeter, then you may remember that terraforming was somewhat limited - players could only level ground at a certain height and create small ditches - an optional gameplay element. In Maelstrom terraforming is less limited, and rather than being the focus of gameplay, it's one of many powerful abilities the player has at his disposal. Now you can level ground at any desired height, dig ditches of any depth and dig up banks of earth of desired height. Also there are a lot different processes that change the landscape automatically.

But these changes are not the only changes to the terrain handling system. We've created a large set of areas with different characteristics - roads, sand, tarmac, grass, etc which have different effects on the units traversing them, including how fast they can move through them. There are zones that drain or restore unit hit points or other parameters (healing zones, gassed zones etc.). And, of course, the terrain itself also affects unit movement -climbing uphill slows them down and downhill fast allows them to gather speed.

The second key environmental feature of the Vista Game Engine is the implementation of dynamic wind and water streams. The streams surround the changeable landscape, interacting with it and with objects on it - destroying them or carrying them along with the flow. Once again, as in real life, wind carries along fire zones, spreading fire across the map, and water damps down fire. The games environment also features dynamic day and night cycles, changing the illumination of objects on map and their shadows in real-time, as well as affecting the productivity of solar power generation which some units benefit from in the game.

The engine has also been generally improved to support features like as skeletal animation, bump- and normal-mapping, fixed LODs (Levels of Detail) etc, which allows us to create very lifelike characters for an RTS.

Physics systems

From the very beginning of Maelstrom's development we've aimed at creating a game with a realistic appearance. And realistic physics were one of the aspects we thought would complement that, especially as the technology was very rare in RTS titles, we felt there was a lot of great potential gameplay situations. First of all, the dynamic liquids and air steams, including their interaction with landscape and various objects, act according to laws of physics. Each stream has a set of properties - such as volume, stream velocity, transparency - that determine stream's behaviour.

Another part of Maelstrom's physics system is the impulse physics. It is used in melee combat and is a part of special weaponry - units get "knocked down" in a fight or thrown through the air by an explosion. Speaking of explosions - we've also developed an interesting destruction model - in-game objects (units or buildings) explode and emit debris, which move according to parameters of the explosion centre. We dedicated a fair amount of time to the development of a rag-doll model, which has added life-like characteristic to unit behaviour.

Complex development

Of course, we've faced some difficult moments during the creation of our engine. The main difficulty with Maelstrom is the necessity of handling many complex processes in real-time - such as alteration of landscape, water movement etc. We've solved this problem by creating parallel streams of data, dividing separate streams for graphics and logic data. This solution has also helped in optimization of the game, and currently despite the processor intensive physics systems, Maelstrom runs on an average gaming PC.

It also took us some time to realise interactive grass (that would interact with air streams and unit moving across it), fog of war (it was a serious task because of the landscape alterations during play) and ice (it was hard to develop an algorithm to display ice barriers). But all these features have been successfully implemented and included in the game.

Bigger then an engine

But what is most important about our technology - is that it's not only a game engine, but a tool set with utilities for game content assembling and editing. Vista includes a number of editors; each of those is designed for work on a part of the game. The Unit Editor is created for managing all in-game objects - from definition of faction types to the last object of every faction. Our Trigger Editor manages the general logic on various difficulty levels - it is used to edit AI behaviour and cut-scenes. The Interface Editor manages the interface creation, including the main menu, in-game interface, and options. The Visual Effects Editor allows the creation of various visual effects - from smoke and waves on the water to "nuclear explosion". And the best thing about the editors is their visual structure. Any task - map creation, working on unit properties, edition of game balance etc. - is handled visually and does not require any additional coding. That is the basis of effective and quality work of map designers, AI scripters and game designers.