Reflecting back on things, it worked.
The aim was to inject the premise of a coincidental freeform magick system constrained by an individual's beliefs and their understanding of the world. In a two hour session, I didn't think I'd have time to explain how magic might work, or what it might be capable of, so I just threw some subtle hints into the background elements of the game...some of which individually looked like blatant hints toward something else entirely.
Given that is was a pseudo-late 1970s setting, the random characters chosen for the session included two hitmen (one brawler, one shooter), a phone phreak (with a jury rigged laptop, in an age when laptops shouldn't exist), a doctor (with a peyote addiction), and a supersitious petty thief (with lucky lockpicks).
On top of the random characters, I tried to set a fairly mundane but dark and gritty setting for the story...Then I repeated several times that this game was more "cinematic" than realistic. That priming seemed to be enough.
Our phone phreak engaged into text based hacking of Proto-BBSs operated by DARPA and pre-hacker activist groups using his acoustic coupler modem. Our peyote fueled doctor went on a vision quest, seeing things that contibuted to leading everyone toward the climax. Our hitmen asked if their guns could continually fire without reloading a la John Woo films, our superstitious thief asked to do healing actions via reiki-style massage. There was also some more potent mystical exertion applied, when all the characters with an element of occult lore decided to work together at one point to focus against a swirling mystical vortex (that the peyote infused doctor was seeing in the sky).
My answer in every case was "you can try", then let the dice determine the fate. If it seemed within the bounds of reality, it was relatively easy the more cinematic and unfeasible it was, the more difficulty I threw at them, but this also meant that such risks instantly furthered the story and got them closer to their goal.
In the end, we found a rival phreak/hacker awakening a monstrous entity in the middle of an import-export warehouse (in which our peyote laced doctor was seeing Nazi symbols everywhere), we saw a minor showdown with some villains. But the time ran out before we could get a serious climax happening, we had a few tokens left in the secrets pool, so that meant there'd still be complications in the characters lives, basically setting things up for a instant sequel, or the beginning of a series... In fact that's what the whole game felt like, the pilot episode for a gritty funky late-70s/early-80s urban magic TV series. A bit early for the movies "Wargames" and "Big Trouble in Little China", but those films were mentioned as pop culture references during the game.