Human hunting and duelling are common themes in fiction. Recommended is Robert Sheckley's “Victim” series. “Victim Prime” even includes a Car Wars-style sequence.
A version that may be well suited to Transhuman space is that of “Button Man”. Button Man (1992) was originally published in 2000AD, notable for being one of the few stories in that publication that did not have obvious sci-fi content.
A hunt involved two button men hunting each other. The hunt was to the death but the winner could instead opt to take the loser's “marker” instead. A marker was one of the loser's fingers. A button man who had lost three markers was to be eliminated.
Each button man had a wealthy patron or sponsor known as a “voice”. If I recall correctly this was because the button man was not supposed to know the identity of their voice and their only contact was by the audio-only medium of phone or radio.
The technology of the world of Transhuman Space will have some effects on the above scenario. Losing a finger is not a much a penalty when such things can easily be regrown with modern biotech. It is possible that the finger will still be taken from the loser in the interests of tradition and symbolism. The actual number of markers a button man has lost will be displayed in an encrypted v-tag, only visible to the other button man within a certain distance.
Drone cameras and body-cameras will give the voices a much better view of the actual action. It is very likely that button men will be required to have upslinks so voices and others can more fully experience the hunt.
In the original story, the protagonist, “Exton” was a down on his luck ex-serviceman. In military systems where most of the fighting is conducted by cybershells or bioroids the human element is chiefly responsible for administration, supply and maintenance. Some current servicemen may be tempted by the prospect of real action. Mercenaries, hit-men or the very poor are also likely recruits for button men. The GM will have to decide if patrons are permitted to use bioroids and parahumans as button men. Similarly, button men with particular biomods, bionics or other enhancements may affect the odds.
Gambling is an important element of button man duels. Patrons are very rich individuals who run one or more button men as a hobby. Substantial bets ride on the final outcome or details of a contest. In the original story Exton's voice loses a considerable amount when Exton kills an opponent rather than taking a marker, as that voice had wagered. In 2100 some button man contests may be accessible not just to the patrons but also worldwide via dark web sites. Upslink recordings of duels may be available through the black market throughout the Solar system.
Button man contests provide many possibilities for adventures. Do the contests actually exist or are they an urban myth or elaborate hoax? Once an idea exists it is likely that someone with enough money will attempt it. Given that contests are illegal, not every button man may have adopted the role voluntarily. An adventure may involve very poor individual(s) being coerced into becoming button men. An adventure investigating the movement of illegal upslinks may lead to characters discovering button man contests. Groups of voices and their button men might also be used in Car Wars campaigns.
The package was surprisingly small, but everything was there.
On top, a black market 9mm MAX pistol without serial numbers. Three spare magazines, loaded.
A one-use data card with the frequencies and other settings he would need.
A couple of neo-amphetamines.
A pair of field dressings and an assortment of lesser bandages and plasters.
At the bottom, the inevitable plastic bag and shears.