I don't mind vampires - as a set of concepts - in the same way I can get along fine with space marines, cyborgs and gnomes, the other subjects of the Money in old tropes series. But with vampires too, more imaginative approaches must be possible.
What are the core concepts? Vampires serve up blood, darkness and time, with a side order of maidens, mesmerisation and strength, and maybe a given geographical region.
So how to see these things differently?
What if it all comes back to the iron in blood - following up Trey's post - and a variant magnetism? Maybe areas linked with vampirism have unusual magnetic phenomena?
It could be these phenomena limit absorption of iron in those not adapted to their effects by a long residence, for example travellers passing through - and then spreading the word. This slow absorption could lead to anaemia, and affect those dealing with even minor blood loss, which might go some way to accounting for the maiden association.
The effect of the phenomena could be greater at night because of the interaction with the local solar wind - which gives us the association with darkness - and perhaps lead to sleep paralysis, which hints at the mesmerisation as well as a relative weakness.
These things could have idiom and narrative grow up around them, and pass into myth, and be mixed with past events and individuals, suggesting immortality and long ages.
The key here is not just a rationalisation, but a new set of factors to consider that could evolve the ways in which the vampire type works, without leaving the audience behind.
But how to get this particular approach into games?
Maybe those who claim to be vampires and those who see them as such are deluded, and the vampirism is a form of ritual passed down the generations, a source of identity and fear central to the existence of a powerful landowning or administrative caste.
In-game it could be that when a nominal vampire attempts to use one of the vampiric abilities, there's a roll-off based on willpower or knowledge, to see whose belief in the effects is stronger or more correct. If the vampire fails, he, she or it is a tired old trope.
If the thing is related to magnetism, there's also potential for area effects or interactions in the environment or from actions or weapons. The ideas on light here might also tie in.
Maybe the vampire niche could just be filled by parasitic electromagnetic creatures, the kind of thing Needles does well, maybe more electrical to tie in with plasma cosmology. They could appear as build-ups of charge, sudden flares or crackling or roiling storms, and even blur the boundaries between items of equipment, protagonist and landscape.
As with the other entries, feel free to steal any of this, shake things up and earn on it.