When the HUD suddenly stood on its head in the browser 🙃

November 7, 2026

With version 2026.10.10 we took two big steps under the hood: the game now runs on Unity 6.6, and the browser version starts on WebGPU wherever the browser offers it, for example in current Chrome and Edge. Otherwise it runs on WebGL 2 as before. Both are ways for a website to talk to the graphics card. WebGL has been around for many years, WebGPU is its successor and closer to how today's graphics cards work. Shortly afterwards, my HUD stood on its head. 🙃

Seen once, then never again. I had opened the game in Chrome on my laptop, and the HUD was upside down. We tried to reproduce it and couldn't. I didn't see it again myself either. So for the time being we closed the case.

Then it came back, with photographic evidence. On October 19 it happened again, in a fresh world. This time I sent a bug report with a screenshot right away. Only the screenshot itself was broken: three copies side by side, full of stripes. The detective work behind it: a picture is made of pixels, and each pixel normally has three values for red, green and blue. The game expected three values per pixel, but WebGPU delivered four, with an extra value for transparency. Read the same data with four values per pixel and the picture becomes readable. The world is upright, but the whole HUD is mirrored: the hotbar sticks to the top, and VEGA's question "Want me to show you the basics?" is upside down. Along the way it turned out that every screenshot from the browser had been broken since the switch to WebGPU. Nobody had noticed, because until then no report from the browser had come with a screenshot. 🔍

Why only the HUD? From the "Medium" graphics level up, with the visor effect switched on, a separate camera paints the HUD into its own picture in graphics memory. The experts call that a render texture. The game then lays this picture over the world with the visor effect and its glow. The tricky part: graphics systems don't agree on where "up" is in such a picture. Some count the rows from the top, some from the bottom. Normally the game engine evens that out. In the browser on WebGPU this sometimes went wrong for the HUD picture. Why only sometimes, we still don't know for sure.

Reproduce it? No luck. To find browser bugs ourselves, we built a little test track. We download the finished game package of a version and start it on our own computer. Then a remote-controlled browser with WebGPU clicks through the menu, starts a world and takes screenshots that our AI looks at. We tried three times like that, with exactly my link and on the same graphics chip, and three times the HUD was upright. Only my real Chrome had the bug.

If you can't force the bug, you have to detect it. So the HUD camera now paints a tiny magenta dot, four pixels in size, into the top-left corner of its picture. Before the HUD is laid over the world, the visor shader looks in both left corners to see where the dot ended up. (A shader is a small program that runs directly on the graphics card.) If the dot is at the bottom, the shader flips the HUD. It masks out the corners while doing so, so you never see the dot. But as long as the bug is hiding, a repair like that is hard to test. That's why there's a test switch that deliberately puts the dot in the wrong corner. Then the HUD has to stand on its head, and that's exactly what it did, precisely like on my screenshot. That proved the detection works. ✅

The obvious fix would have been a bug. "Then just always flip it on WebGPU!" We tried that on the test track before building it in. It would have broken the HUD for everyone, because most of the time it was upright.

Three traps along the way. WebGPU played a few more tricks on us. First, a simple copy step can mirror a picture on WebGPU all by itself. So reproducing the bug with a mirrored copy didn't work. Second, a new switch we wanted to hand to the shader once simply never arrived in the browser. Third, we read pixels back to check the order of the rows and got contradictory answers. So the shader now writes its verdict into one single pixel, and we read that. A single pixel has no up and no down. 😄

What you get out of it. Since version 2026.10.24 the HUD in the browser is the right way up, and screenshots from the browser are real pictures again. Bug reports now also carry a graphics section that says, among other things, which way up the HUD was. So next time we'll know even without a picture. In the same package we also fixed a bug from Lyxette's reports: an animal no longer floats above a ditch you've dug out. 🐾

If you still see the HUD upside down at some point: in the browser, F2 opens the bug report. We'll take a look. 🙏