This is a fantastic game! I absolutely love the core mechanic. This could seriously be a super addicting fun game. I think the constant risk of losing some or all of your dice is definitely a very make-or-break aspect for most players. It might be nice if the odds weren’t so entirely stacked against you. Since you have to survive many rounds against the boss, there are LOTS of opportunities to have things go wrong. Maybe instead of each box having a goal for a sum of dice, there’s a goal for a certain number of dice? That way there’s just one less variable for players to lose against. You could also consider having the crab delete the dice at the end of the roll not the start (not sure about this once since I think the idea of losing your dice is pretty huge to the gameplay). Or maybe a fourth slot that doesn’t have any rewards that just reduces the chance of the crab actually deleting your dice?
Regardless, with some polishing and some tweaks, this is an incredibly addictive game!