Thanks for your comment!
In fact, I had spending like 70% of the time trying to find a solution to the issue of this game mechanic.
When I finally figured out some way by referencing the game "Dicey Dungeon", the deadline is just so close. And the mechanic change involves lots of coding, so I gave up few hours before the deadline and went to sleep. (had to work the next day)
Eventually, I chose to accept my failure, I wasn't really satisfied about the result.
But I guess the result isn't that much matter, the process of making this is. I would probably work on the mechanic change some day, if I think it's fun enough, I might release it as a new game!