other than adding more 2 oc and making early rimuru stronger almost nothing really changed other than that, oh and also when veldora got absorb by the other oc villain?, i see no change from chap 1 to 15, i just got tired reading it cuz you know i read the original novel why would i read it again when I'm trying to find a ff version, plus the mc is very childish maybe autistic his patience is none existence a lot of monologues the other character don't talk much, and like i said every thing is just like what rimuru do in the original novel the really differences between the two is just him having knowledge of the canon but he still follow the script when he can at least change it even his name is rimuru.
average ff,good novel for newbie reader and also for those who didn't read the novel, that's all