The Best Games Engines for AI (2019) | AI 101

Key Takeaways

in recent years videogame engines have become increasingly more accessible for developers all over the world what were once expensive pieces of software adopted solely by the triple-a video game industry these are now readily available to anyone with a desire to learn how to make their own games but a common question that comes my way is what engine should you use if you're going to try and build a certain type of AI system for a hobby project or what tools are available and your chosen engine as you're starting out I'm Tommy Thompson and in this episode of AI 101 we're going to be looking at some of the most popular video game engines on the market and 2019 and what artificial intelligence tools and technologies exist within each as well as some suggestions for the types of games you're trying to make now let me begin by saying I don't think there is such a thing as the best engine to work with let's just get that over the way each have their own strengths and weaknesses and are catering to different audiences my aim is to give some insight for those of you keen on starting out as well as provides sufficient kindling to start flame wars in the comments but in addition there is a huge disparity between what a I tools are available to developers depending on the engine they decide to work with naturally AI isn't the only consideration you have when making your games and typically it's much farther than the totem-pole when you consider a programming language source code access physics tools animation and rendering pipelines and much more but it is something worth thinking about depending on the design of the game for this episode I've decided to focus on engines that are available to the public either for free or under a license model that's largely accessible game maker studio CryEngine unity unreal good ole and source so let's work through each and turn and discuss the benefits and drawbacks and even some notable examples that indicate the type of work you can pull off using these tools so first up let's talk game maker a fun and flexible 2-d game engine that's readily accessible for novice developers despite this it still provides plenty of functionality for more experienced developers to shine with notable releases in recent years built in the engine including nuclear throne gunpoint 10-second ninja x hyper light drifter and minutes game maker has one knowable AI tool the motion planning system any 2d game intent on having non player characters in it needs to address one critical issue how to have them move around the world this could be to hunt down and fade the player to follow you around as an assisting character or just run a patrol around the space the motion planning system enables for navigation paths to be calculated but with different variations there are three motion planning function types linear potential and grid linear is really simple it just calculates the straight-line path to reach a given destination and start making motions towards it in this instance is looking for a clear straight-line path the heads directly toward a subjective but doesn't really factor obstacles or anything in its way meanwhile potential is calculating paths that tried to go around obstacles this is based on a principle of potential fields where by obstacles repulse the moving object as if they were both magnets you can configure how far it's allowed to rotate around a given obstacle point and lastly the grid approach is using an a-star algorithm to compute a path between start point to end having broken down the environment into a 2d grid and it will then calculate the path along that grid that's as optimal as possible next let's check out unreal an engine that has transformed much of the games industry in the past decade becoming one of the most viable options for Studios ranging from Indies all the way to the biggest studios in triple-a Unreal Engine 4 is now completely free to use given epic games as making all the money on earth courtesy of fortnight but there are still royalty payments due should a game exceed earning thresholds when published or if you host it over on the epic Store which I'm contractually obliged to bring up so someone can complain about it in the car and I get my epic exclusivity money so let's talk a itools first op ue4 has navigation measures while game maker works with navigation on 2d surfaces nav meshes are what we use for movement on 3d surfaces the navigation volume tools allow you to define whole areas of your game level as navigable for an AI character as well as justify areas that are more expensive or less desirable to walk through after that you can then call the navigation tools to have your actors move around the map like all of the AI tools in ue4 you can either interface with the navigation through C++ code or you can do it through the blueprint visual scripting tool if you need to learn more about navigation meshes be sure to check out the first episode of AI 101 which talks about them in much more detail next up is behaviour trees arguably the most commonly used AI tool for managing the behavior of a character or system in modern games behavior trees have largely been standardized throughout the industry an epoch I've done a great job of continually updating these tools to better reflect our developers seek to use them you can build trees of startling complexity reliant on one or more blackboards to store information that your characters can utilize behavior trees with the focus of the second episode of AI 101 so yeah be sure to check that 102 if you want to learn more working in tandem with the behavior trees is the environmental query system or EQs let's tool allows you to gather useful information you might need for a behavior tree to make decisions such as where enemy targets or items are located prioritizing enemies based on specific properties and much more the EQs system is highly flexible and it can be used to provide information for a variety of different situations in addition to this there is the AI perception component that consolidates sensory information for actors this includes been able to see enemy and friendly actors been able to hear noises whether they've received damage from an external source or even if they're being touched by other actors that's not meant to CERN as creepy as I wrote it but yeah they can sense being touched unreal zi tools are arguably the best among all publicly accessible engines for what is typically required in the triple-a gaming space but that doesn't comprehensive despite that one of you ephors biggest strengths is the access to the engine source code thus allows for developers to build new tools that integrate with an existing engine framework and can really streamline development a good example of this was highlighted in my second episode on the a IFC of Thieves but the team explained how they wrote a separate navigation system for sharks given underwater navigation isn't supported by navigation meshes however given the developers integrate to the end to the existing navigation framework it meant they could operate it and it could be called in blueprints and behavior trees much like the normal navigation tools it's pretty cool given we just looked at unreal let's take a look at unity an engine that is immensely popular with students indeed eV and even some larger studios given the cost and relative ease with which to prototype games and cross-platform development it's arguably the biggest competitor to Unreal Engine at this time with the features in each engine our laning more and more with each new release despite that unity is at the time of this video in a weird space when it comes to a I like Unreal Engine it has a fairly comprehensive F occasionally limited navigation mesh system that has many of the same features as unreal but one key differentiator is that real time nav mesh baking whereby you recompute the nav mesh during gameplay isn't supported in unity by default however new nav mesh tools are available via the unity github pages and well it seems these new tools will continue to be developed over time none of it has been built into the main branch just yet the disappointing thing is that right now that said unity lacks tools for managing more complex behaviors such as finite state machines or behavior trees however unity is investing tremendous resource into new AI research to build new tools that could later be integrated into the engine so while at present the engine out the box doesn't cater to a lot of the meat and potatoes of game development there are two exciting tools currently in preview that you can use right now the AI planner and the machine learning agents toolkit the AI planner is designed to provide means to which to build domain models that can model a situation abstractly then make plans that can to keep solutions to solve problems with the GNAT encoding this is very much akin to popular AI tools such as the goal-oriented action planning method popularized by fear in 2005 the AI planner is still in preview at this time and only accessible in unity 20 19.2 onwards and you can download it using the package manager I'm still playing with it myself but it seems to provide a useful collection of tools for modeling domains visualizing plans it's created managing execution at runtime but also being able to handle continuous and ongoing tasks this is achieved through use of trial based heuristic tree search a generalized implementation of Monte Carlo tree search which appeared in my episode of AI in games when I looked at the AI of total war Rome - this is a really exciting idea given it will allow for the system to handle situations of uncertainty by simulating the possible outcomes and then plan accordingly meanwhile the machine learning agents toolkit seeks to allow for developers to train machine learning agents or brains as they're referred to in the engine through use of tensorflow an open source library developed by Google for training neural networks through reinforcement learning thus requires users to install a working Python setup whereby you then train the network's through this then later deploy the trained AI brain as part of the main game this late planning is still in an experimental phase but could prove valuable once the tools flesh out a bit more one of the most interesting challenges this faces is integrating the tools for training and testing new machine learning agents into the Unity engine itself this is continuing to be improved with new integrations into the opening a gem as well what's more interesting to me is that the UI and features are built to accommodate this notion of training brains to solve problems within your game and I'm curious to see how developers will take to that in the coming years next up let's jump over to CryEngine another feature-rich engine aimed at the triple-a market largely popularized by the crisis series the husband and games ranging from pray to everybody's gone to the rapture it's worth mentioning that there's also Amazon which is essentially a separate branch of CryEngine built by Amazon game tech but with new net code hooks specifically enter Amazon Web Services and twitch as well as VR integrations I'm gonna be focusing on the tools and CryEngine for now there's a lot of overlap and CryEngine with what you'll find in unreal which is no real surprise given they're both vying for the same corners of triple-a game's development but the actual implementation varies quite a bit and is governed largely by cry engines focus on making 1st and 3rd person shooters you have navigation areas that users can define by hand which can then be utilized by AI actors actors can be controlled through behaviour trees that can be defined in XML or on a visual editor and a unique take on gathering environmental knowledge for your AI known as the tactical point system or TPS TPS is much like the EQs system in ue4 and allows AI to ask intelligent queries of our objects or features of the local environment this is great when you need AI to quickly calculate cover positions that will provide sufficient defense prioritized by distance on whether other AI characters may use them arguably the most interesting unique feature of CryEngine as the AI actors can be assigned to territories and waves territories are volumes of space bill and editor that are part of what is called an action bubble when a player enters an action bubble only AI actors within that territory will be enabled at that point in time in addition an AI actor in a territory can be assigned a wave for spawning N and fighting against the player with new waves only spawning under specific conditions this effectively manages the spawning destroying initializing and debugging of AI actors and is very useful for creating specific combat sequences on top of all this there is also source code access for the engine so if you need to add and tweak any tools to suit your needs you can jump in and play about in the C++ code base last of the big engines out there as Valve's Source engine which has been used by the publisher for their titles ever since 2004's counter-strike source and half-life 2 up to recent releases such as artifact and dota under Lords but it's also used by other triple-a developers most notably Respawn Entertainment for both titanfall games as well as apex legends the public version of Source engine is accessible from Steam itself and is ideal for making your own mods to many an existing valve game but the costs for subsequently making a game based in their engine are a lot higher given you not only need a source engine license but you need to pay havoc whose physics tools are part of the engine $25,000 before you release the game so yeah stick to mods or go try another engine if you're serious about making a game for sale sources tools for AI are largely an extension of that used in half-life 2 so it's really focused on non player characters that fit first-person shooters but much more layered with additional tweaks and options available that still stems from the fundamentals of the original game which I covered in the AI 101 episode on finite state machines with tasks conditions and schedules all largely still operating in the same manner as before here there are new editions with the ability to define behaviors that are effectively genetic schedules for different npcs to adopt as well as the ability to manage the memory of AI characters and establish relationships between them memory allows for information such as last time the player was seen or last-known positions to be retained for periods of time while relationships help with squad management and team combat given an AI character on the whether or not they like hate or are scared of another character in the game it seems like an ideal opportunity to play around with if you're just keen on making small mods however I will warn anybody who's keen to try it out none of the AI is properly documented by valve there is a community written wiki which caters to some of your needs but it's not entirely fleshed out last one on the list is good ol a free and open source engine which started development back in 2007 and launched version 1.0 in 2014 it's not as popular or as pervasive an engine as the others listed above but it has a growing community of developers including school kids in the United States and there are a small number of games emerging based on the tool there isn't much to show here beyond some pretty useful navigation mesh tools with a lot of tutorials out there to help you build simple stealing behaviors or finite state machines one point to mention is that given the engine is open-source the community does appear to be working on new plugins and tools that could add more features I even saw tensorflow integration similar to that found in unity that slowly been developed but I didn't find much else when conducting my research for this video that said a figure should still give it an honourable mention this is far from an exhaustive overview of the EEI tools available in game engines there are still engines I didn't cover and I may have missed something in the ones I did if you have any thoughts be sure to share them with others in the comments but another factor is that so many games are built in tool chains that are not available for the public to use most triple-a developers or publishers have their own internal engines that are being continually updated to enable for different experiences via EA's frostbite used in everything from battlefield to battlefront to anthem and FIFA give a soft snow drop used in Tom Clancy's division and Mario and rabbits kingdom battle and even the ed tech engine used in rage Wolfenstein and doom despite that hopefully you've got a grasp of what each engine can do and if you're an aspiring game developer or researcher you've identified one or two engines you'd like to play with thanks for watching this episode of AI 101 if you liked it push all the buttons and join my wonderful subscribers and supporting the show and helping it grow and keen to come back and do another episode the more AI technologies are missing for game engines to let me know in the comments if you'd like to see that episode as it's an increasingly long list a special shout-out to my supporters on patreon who not only continue to support this show every month and make all this possible but it was a discussion in our discord server that led to this episode being made along with some valuable feedback on the way you can join all these wonderful people on screen now by clicking the links in the description have a good one folks I'll be back [Music]