Things I would love for 6.0 deep dungeon
1.) Allow party members to be replaced with another member of the appropriate role as long as they are at the same floors as your fixed party.
2.) Create secret alternate paths with special rewards and special level designs. (Like binding of isaac has hell, heaven, etc.)
3.) Create Notorious Monsters within floor sets.(special bosses)
4.) Create special power ups/abilities when playing solo.
5.) When party members disconnect add a trust or trusts (if multiple party members are gone.) That stick with you until the party members come back or you complete fail the floor set.