GPT-5.3-CODEX: New Codex App (Building a GTA Game)!

Yesterday, I went through all the technical stuff about the new GPT 5. 3 Codeex model. Today, I actually want to show you how this thing works, and I've got the new Codeex app dropped by OpenAI open here, and we're just going to build some stuff, mess around with the skills and automations, and see what happens. So, let's get into it. Okay, once you're

in the new Codeex app, what you'll notice over here is that it looks pretty simple, and it's meant to be like a chat interface, but it's very powerful. And on the side over here, you have a couple of things. You have the ability to create a new project, automations, and skills. So, let's take a look at skills first. Skills are basically instruction packages that extend what codecs can do. There's two sections here. At the top, you got installed. These are the built-in skills like skill creator and skill installer. That below is the recommended. These are skills that you can add. You can see there's stuff for CloudFare deployment, Figma integration, working with notion, managing linear issues, generating images, a bunch of different things. So, a skill is basically a folder with a skill. md file that has instructions for codecs. It can also include scripts, documentations, templates, whatever codec needs to do that specific task. Well, the easiest way to get new skills is to use the skill installer. You just tell it what you want, like install the linear skill, and it'll grab it from the GitHub skills repo. Or you can make your own with the skill creator. Just describe what you want the skill to do, and it'll set it up for you. When you're working in Codex, you can call a skill by typing a dollar sign and then the skill name. For example, if I type the dollar sign, you can see I have these two skills installed at the moment. So, I can call the skill creator one, the skill installer. Codex can also pick up skills automatically based on what you're asking it to do. The nice thing is that these stick around once you got a skill set up. Codex just knows how to do that thing from then on and you don't have to provide instructions all over again.

There's also a new feature called automations. So these are scheduled tasks that run in the background automatically. So when you open this up, you get these templates to start with. You can see examples like scan recent commit for bugs, draft weekly release notes, summarize CI failures, all kind of things that team actually need and use. And each template is basically a pre-written prompt that Codex will run on a schedule. You can use them as is or customize them. You can also make your own automation. So I'm going to make one to show you guys how simple it is. So at the top you'll see the new automation button. I'll click on this. I'll give it a name called error log monitor. And basically what this automation is going to do is going to check for error logs every hour. And you can specify a folder you want this automation to work in. I'll just put it in this folder for now. The universe of AI. And the prompt I'm going to give it is check the logs folder for new errors. Categorize them by severity and create GitHub issues for anything critical. And then you can create a schedule. You can do daily. You can select the type of the day and everything. Specify the time as well. For now, I just keep it at 9:00 a. m. But you can also do interval, meaning like you can run every 24 hours or every 16 minutes, whatever specified amount you would like to do. You can do that over here as well. I'll just keep it daily and just press create. So that's it. Now I have a error log skill that monitors any errors that happen and I get notified without me having to go there and manually check on everything

happening. All right. Now I'm going to try something crazy. to make a GTA 6 game with codeex. So, I have my prompt ready here and I'm going to paste it in, which is going to be build me a top-own GTA style game in the browser. Here's what I want. I'm telling it to make it a 2D view with a player character that can walk around, drive cars, anything like that. Simple city map, basic police system, WDs movement, and everything like that. This is going to be tough. So, I don't know what the result will be, but let's see what it does. And we also have the GPT 5. 3 codeex model selected over here. So, you have the GPT 5. 2 21, the older one, everything like that. I select the top new model which came out yesterday. And then you have your reasoning. You can set it to low fast responses with lighter reasoning and obviously extra high. I'll keep it in a middle ground. So I'll choose medium. And then I'm going to do it on my local so it has access to this folder which is on my local desktop and it will run it through there. And then what I'm going to do is I want to before I enter this prompt, I want to add a specific skill. The skill I want is to develop web game, right? Cuz obviously I want this to be a web browser. So, I'm going to add this skill. So, I just press install skill. And just like that, I have the develop web game skill installed. Then I'll go back to my folder over here. And then I'll also add the skill. So, if you guys remember, all you have to do is press the dollar sign. I'll press that. And I'll add that develop web game skill. Then all I'm going to do is press enter. So, let's see what we get. This is the GTA game that I created and it's called Neon Vice Tiny City. And you can see I can move around using WD, E to enter and exit, space for action, click to aim, so I can, I guess, you know, aim. I'm not going to say the word here, F for full screen, and then I it's telling me to stay hydrated and moderately criminal. So, so far it looks good. Let's actually play this. So, I'm going to click on the start mayhem button. So, this is my guy. I can move around. I can move my arrow. I guess these are supposed to be pedestrians. Mission borrow any car legally. So, let me go that. And in order to borrow a car or enter is to go E, I see. Oh, these are the cops, which is kind of cool. Let me go full screen. Okay. And then you can see we have the map over here, which is crazy, guys. This is the map. And you can see it's tracking it. It added that feature. I just prompted it. I didn't know if it was actually going to do that. So, let me enter this car. Okay, now I'm in the car. Okay, I can move around. Oh, I just hit someone. I hit more and looks like the cops are after me. Okay, this is sick. The cops are pretty slow. Why this car is kind of slow as well? I want to get into another car. Oh my god. No, no, no. They're close to me. Let me exit. Go in this car. Yeah. Can I Oh, now they're after me because they just figured out I was there. I ran over. This car is way faster than the other ones. And yeah, this is kind of sick. Okay, it looks like the cops caught me, but I can even uh I can even, you know, use my things over here and do what you guys are seeing me do. I don't want to say the word just in case I get banned on YouTube, but let's try that again. And then there are missions here. Obviously, we don't have time to go and accomplish all the missions, but this is kind of sick cuz like this was just created from a simple prompt and it made it. and like is using the new model is using codec. So this is sick. Just imagine if you customize this, work on it for a couple of days, maybe give it some digital assets, you could actually create a simple web game that you could maybe deploy or even a web application or a phone application that you can monetize. So this is very good and this is powerful. What you're seeing right now

is somebody making a Minecraft clone with GPT 5. 3 codecs and it's only using 3. js. So let's see this in action. So, I'm going to set this to the beginning. So, you can see like from the beginning like the map looks pretty realistic similar to how Minecraft looks and you can place objects and you have option for multiple different you know elements that we see at the bottom over here and once again this was oneshotted like he just put this in gave it probably maybe one or two digital assets I don't know what exactly the prompt was but it's just using 3. js JS and is able to create something like this. And just imagine if you work with Codex for a longer session and you give it multiple, you know, properties, give it multiple digital assets, give it access to other powerful tools, you can probably create something that could be ready and like if enterprises are using this like game developers, they might speed up their whole game development process. Who knows? It's calling it VoxCraft, which is kind of funny, but this is sick. One

thing you guys probably noticed during the video is that I'm using my MacBook Air. So, it's not the best laptop for this type of production and it was still able to create something crazy. But currently, Codex app, the one app that I'm using and showing in today's video, is not available on Windows. But luckily, what seems to be happening right now on Twitter is that there's a leak that Windows has been achieved internally, meaning that the Windows app is almost ready for deployment and is going to come to the Windows operating system soon. So, if you're watching this video and if you have a Windows laptop, when this comes, try it out. If you already have a MacBook and you've tried out this app, what have you made? Put that in the comments as well. Make sure

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