Thanks for your very detailed feedback! The overflow bugs are most definitely expected since I haven't started to work on what happens once numbers get really big. But your UI, gameplay feedback is also very useful and can definitely be improved. In particular, I very much agree with the inventory/shop button confusion, I should add a section in the shop for buying materials instead of clicking icons in the inventory, very unintuitive.
As for fighting, I hope the next update with an overhaul on its mechanics will make it a lot more interesting.
I'll also make sure to come up with something creative to bring more freshness on your 10th+ runs.
I'm glad you like the DR and the OP-meter system! Not many people have mentioned that haha.