Monsters then. Lots and lots of monsters. Zap them, pick up all the loot they leave behind, move on, and zap more monsters.

This is a strangely addictive game that is not exactly up my street, but I can see why so many around the world are in to this franchise.

Well, they are demons I guess rather than monsters, and the battles tend to be circular. They come at you from all sides as you take a three-quarter to-down look at your underground battlefields.

Spin, twist, zap, do it all again.
OK, some story to put some meat on this. Apparently, and I am no Diablo expert, this is all set some 25 years on since the last one.

Then, the Prime Evils were defeated, but you knew back then that would not last. Seems banishing them to Sanctuary wasn’t the great idea it sounded like. Sounds like Sanctuary is a great place to be banished to.
Falling stars, the town of Tristram and all sorts of other omens all conspire against you, so you get to spin, twist and zap monsters. Sorry, demons. 
You can even do it with a few mates or solo. Up to you.
Level up, fight even bigger demons among some of the most lovely light effects ever.
It really is a colourful experience zapping demons – you can understand why it’s so popular.
Perhaps at the end of this outing, you can just forget about the banishing and just finish them all off once and for all, and then no one will wonder about Diablo 4. 

Wait, that doesn’t sound like a great business plan.