The players are haunted by the ghosts of the villains they've killed

>the players are haunted by the ghosts of the villains they've killed

How can I have fun with this?

Harmless curses and generally being dicks to them. A bonus if they can't exorcise them.

>the players
>not characters
Well I haven't killed anyone yet, so as long as I don't start I should be okay.

>one of the players isn't being haunted.
>there's a very conspicuous absence in the ranks of ghosts
>only one of the players can percieve the ghosts
>the ghosts had projects underway they want the players to complete
>the ghosts mention their treasuries and that it's such a waste that they'll be forgotten for centuries until some undeserving explorer stumbles across them... no, of course this isn't a trap, but can you risk the macguffin I had stored in it being found by another?
>the ghosts keep bickering about which one will fall to evil first

run it like that one episode of the original Teen Titans with Slade's ghost. Make the players unsure if the ghosts are a tangible curse or their own subconscious guilt

Have the ghosts play out scenes from their past before they were villains in order to humanize them and make the player question whether they were justified in actually killing them

...

Watch Stardust

Voyeurism

>"duuuuude you kiiilllllled me what the shiiiiiiitttt~"
>"yeah but you were horrid, though"
>"stiiiiilllllll"

Snark and quips all the way down.

Make it cynical and judgemental.
"Oh yeah, drink the mystery water. SEEMS GREAT, YEAH"
And never forget the narration.
"The rogue sneaks up on the unaware ork, preparing to strike. The ork only needs to make a 180 degree turn to save himself"

"Hey, hey, Warrior Woman! Bard's trying to look at yer knockers again."

"The rogue is now placing poison into the king's cup. It would be very unfortunate for this man if the fact was mentioned aloud by a disembodied and DEAD villain.

"In fact, isn't that how YOU wound up KILLING ME? Bit of a one trick pony aren't you?"

You have to leave two coppers on the eyes of those you kill, to pay for their voyage to the afterlife.
Any time you don't pay the 2cp, or steal it from someone waiting in line (the lines in the afterlife are loooooong), their ghost is stranded.
If you have ghosts around you in an area with enough latent undead magic, you start seeing shit.

If you walk into an area with extreme amounts of undead shit going on (say... the bowels of the BBEG's lair), BOOM! Army of vengeful ghosts.

Make them act like Statler and Waldorf.
>Well I thought that combat went pretty well!
>You mean they won?
>No, there's less of them to look at now!
>DOHOHOHOHOHO!

>I think it might be that barbarian lady's time of the month!
>How can you tell?
>She had an extra Rage today!
>DOHOHOHOHOHO!

i like it

>Oh... ohhh...
>What's wrong with you?
>... It's either this guy or indigestion. I hope it's indigestion.
>Why?
>It'll get better in a little while.

>"Hey PC."
>What?
>"I just figured out your style. You fight like So'n'so."
>So'n'so's not a fighter.
>"And?"

>Oh yeah? I'd like to see cast 'good' magic.
>"You first."
>Oh you think you could do better?
>"I couldn't do worse!"

>I'd like to see you fight these things!
>"Yeah... We should."
>Oh yeah? Can you swing a sword?
>"No."
>Can you fire a bow?
>"No."
>Can you cast magic?
>"No."
>Then what would you do?
>"Exactly what you're doing!"

The ghosts appear to the characters individually and try to pit them against one another

...

Make them "helpful".

Statler and Waldorf vs Milton Berle, absolutely terrific.