About making my own enemy

[MulleDK19]

So I assume it's possible to make out own enemies? Like, it wouldn't be easy perhaps, but it's possible right?

Because I was going to make one, but I'm not sure what programs and stuff I need to do, so is there some guide for making enemies or something?

You cannot make completely new enemies.

You can copy the original, and then change some attributes, like moving speed, how long to look for the player, their mass, field of vision, hearing ability, health, what music is played when they're close, etc.