Neat idea. I think it would be a lot more fun if the system was simplified though. Having to freeze in place, sort through an inventory, and equip items didn't feel like it meshed well with a retro 2D platformer.
Viewing post in Oliver the Dice Master jam comments
If my opinion matters at all, I'd forego the menu altogether. Instead of the buttons being Open Menu and Attack, I'd have 3 buttons: Attack, Equip Next Die (cycle through them), and Reroll Current Die.
Opening a chest automatically fills up as many dice as you can hold. Because why would you not want to take a die? And your dice are just permanently on the HUD, like in the corner of the screen.
And if you want to get rid of a die, you just press Attack and you'll uselessly throw it away, like throwing away a weapon in Breath of the Wild.
But that's just what I'd do! I don't want to tell you how to make your game.