The PCs are set up by somebody. They are arrested for something they either have
committed in the past or not committed at all. This could be a fight, possession of illegal
goods (that could be smuggled onto them), hiding a criminal, etc.
They (or most of them) end up in the arena
and have to get out before they face an enemy that is too large for them (there will be sabotage
involved so some of their gear will be affected...).
There are different ideas on how to go from there:
The person that got them into trouble wants the PCs to do a dirty job for them (e.g.
smuggle something or escort someone and make sure that person is not guarded properly when an
assassin attacks). In return they gain their freedom.
Something out of the ordinary happens that gives the PCs a chance to escape (riot, somebody's
powerful special powers going wild, overminds doing something weird).
people on the outside and on the inside of the arena manage to uncover a plot. if the people on the
outside manage to contact/warn the right people they will have the power to set the PCs free.
Lots of people got mistakenly thrown into the arena because some overmind is more than its
usual share of messed up. But other strange things happen in the city, too...
Every mega-city maintains a fleet of "sandhunters" who look for drakonium, strange
energy crystals which are needed as power source. Drakonium is sensed by psychers and
every fleet needs them - the more sensitive to the substance, the better. This fact is
not known to the people of Prometheus. The rulers disclose that while they hunt down psychers
mercilessly in the city, they employ (or enslave) them to find drakonium. Sometimes psychers
are even used to maintain over the sandhunters to prevent rebellion or desertation.
If they have a name, the characters are either confidentially hired to escort an important
psycher to a drakonium harvester. The fact that the person they are escorting is a
psycher might not be disclosed to them. The psycher can either be a volunteer or a convict
who will try to escape.
The characters could be convict themselves and have to escort the psycher to redeem their
citizenship or to escape death in the arena. They have to keep quiet afterwards about the
psycher, but having grown up in the streets of Prometheus they know that as soon as they
come back or deliver the psycher, they will be executed to make sure the secret is kept.
The characters are slaves on a drakonium harvester. They are either psychers or
"ordinary" workers. A/another psycher contacts them and tells them about his/her plans to
escape. He/she wants their assistance.
The characters are working on a drakonium harvester. The main psycher on the vessel
either gets possessed by a demon or shows other dangerous abnormalities which affect life
on the harvester.
The psycher(s) on a harvester becomes aware of something outside. This might be
an especially potent source of drakonium, a drakonium source which is protected by something
e.g. a group of people/entities/mechanisms/traps, or another strange landmark or phenomenon.
The characters could be scouts to find out what is going on outside.
The characters are either hired to track someone/something down or are doing it
because they have seen a notice or have their own personal reasons. The object could be an
intelligent robot (panzer) intent on destroying a certain type of human/post-human/mutant/alien/robot/etc.
Somebody fearing for his life could hire them as he/she has received warnings...
Somebody hires the characters to protect him/her. He/she tells the characters that
an intelligent robot is trying to kill him/her. In truth the person who hires the PCs
committed a terrible crime for which he/she is hunted by the creature.
The characters are hired to track someone down. What they don't know is that the person
they are hunting has undergone a mutation while on the run. The mutation can either give
the hunted person special powers it can use against the characters, a different character
(for the better or worse) or the person has mutated almost beyond recognition. In the
last case it might be an idea to make the person a certain type of criminal who after his/her
transformation keeps on committing the same kind of crimes. This way the characters might
be able to find him/her.