Great game so far, love the art.
But, there's a huge resource utilization problem. I personally watched my browser's CPU load spike to nearly 60% util with no other demanding apps running, and I have an i7-14700k. I've run 3d renders less demanding than this game. I believe that's the reason Opera doesn't seem to "support" this game; Opera limits the amount of PC resources that any given web application can demand, and any web app that demands/needs more will fail to run.
To be frank, it's grounds for suspicion that any in-browser game would be more demanding to a CPU than most cinebench tests. But I honestly think that it's probably just a resource targeting and utilization issue; even my CPU's IGPU was left untouched, much less my discrete GPU. Regardless, this absolutely needs to be addressed as the performance is relatively poor; it still runs extremely slowly in browser in spite of the CPU load, as if it's running an individual check on every pixel every frame and loading that all to the CPU.