For the small casual games I've been vibe coding, I always start from a place where the application has a CLI where it can run headless, rendering to offscreen texture, with a a screenshot command as well as performance instrumentation. It takes no time to include all this, and gives the agent a way to automate the ui and inspect important things. It also lets me trivially have the agent update screenshots.
Not as neat as being part of the build process, but I will now add that.
I have an offscreen screenshot path, as well as a CLI arg for world pos/camera view vector, and scripted benchmark runs with a simple text-based input format that has rows of named segments of n game ticks length with control inputs per segment. Use that extensively for A/B testing of visuals and performance while working on the game code.
Agent can't _play_ the game yet, but that's on my list to experiment with.
We had such a vibrant indie game scene when Adobe flash was about and since then nothing's really touched that level of ease of development. I think vibe coding is the first tool that actually exceeds it.
And for those of you: https://XCancel.com/search?q=%23vibejam&src=typed_query
In some cases it does. Which engine?
Right now I have my own framework which has a host written in Rust but game code is written in AssemblyScript - too early to tell how well this will work out but it is very promising to me right now.
If I were just getting started I would probably pick some framework in Rust, or maybe Bevy which I believe is considered an engine but is code-centered.