Love the sprite and UI art, the palette order effect on attack is really cool. Interesting gradient pattern in the background, seems to be a theme in my recent game picks, was it done by hand?
Gameplay wise, yeah a tell would've probably been too easy for this game loop. The Pet Rocks minigame in OMORI did a twist on rock paper scissors with bonus damage for winning consecutive turns, so there may be more ways you could riff on the base idea. I would have liked to loot the monster's gold after defeating it.
I had the same WebGPU issue, luckily saw it got addressed in the comments. The UGLY GIANT is awesome, I gave it a shot on my mobile before fixing my browser, nice that the touch buttons worked but it didn't scale to my screen size. (I did a touch Game Boy myself and spent like half the jam making it responsive instead of working on gameplay or art 🥲) I liked how the buttons animated in response to keyboard inputs. Very nice of you to link your source code, I'd love to learn more about WebGPU and how you made the custom engine.