Omikron: The Nomad Soul, which I am actually playing now for the first time, is strange in same futuristic terms that Blade Runner is, but still interesting to play nonetheless.
However, in term of weirdness, one of my favorite would have to be FREDDY PHARKAS - FRONTIER PHARMACIST. Or maybe that qualifies more as the silliest concept, rather than weird. I guess it depends on your perspective.