The game worked perfectly on browsers in iPadOS 17 and prior.
After upgrading to iPadOS 18, the game is broken in all browsers.
So probably something to do with webkit?

During the opening cut scene, no text appears, but you can still advance the story and panels by pressing the return key on a connected keyboard.
Afterwards, the menus and character picker work fine.
But once the first level launches, the first frame stays frozen for the rest of the game.
There is no further animation in the main window.
But, you can tell things are happening because the counters on the right still change if you fire or use bombs.

I’ve included a couple screenshots with the log open.

Device: iPad Pro (12.9”) (3rd Generation)
OS: iPadOS 18.0
Browser: Safari, Firefox, Chrome, etc.