the gods are physical beings, existing within the world and can be talked to and/or killed
there is no turning undead
spellcasting doesn't even use levels or slots, spells just work or require an expenditure of HP or ability score loss (draining STR or CON) or something that replenishes with rest
spellcasting is something anyone can do if they have the right stats
there are no classes
only humans
static DCs for d20 rolls
equipment and gear more important than stats
exploration is more important than fighting
combat as war
leveling up is an explicitly magical THING that you have done to yourself, it doesn't happen often but could be something characters work towards
lore is baked into the world, if the Magic Missile spell exists then people know who created it, where it's been used, and how they might find it
I have no idea if any of this is doable, but I'm going to try