i think u can make some sort formation too so we can create formation and with button when we click it will make flag as center formation what we create
example : 20 x 20 tiles
i add 4 warrior at outside tiles mid healer and inside archer at 1tiles from center formation build from 20x20 tiles and when i use it it flag will appear and our warrior healer and archer will go to their position and we can make hold button or nope if hold button used it will hold at that position if not they will come to enemy who near him and back to position after that or if enemy to far
u can try make upgrade job like warrior > knight and add facility like stable etc also monster who can summon monster or boss from low floor
and make story too to make it more interesting
Thanks.