The “quantum jumping” game is probably going to be the lightest, most free-form of the ideas discussed so far, primarily because it’s so wide open. The real kernel of the system is going to be a currency arrangement whereby character resources can be exchanged with conditions attached. I had a bit of a brainstorm as to how this might work, inspired by a minor rule in the forgotten RPG Immortal: The Invisible War. For those not familiar, the premise is that you – the game assumes you’re playing yourself – discover that you are an immortal being who had suppressed your own memory in order to live as a mortal but are now reawakening to your actual nature. Experience points in that game are thus called “memory” because you’re not picking up new skills – you actually are just recovering abilities you’ve already attained throughout your millions of years of existence.
A novel spin on a classic mechanic on its face, to be sure, but there was another innovative twist: it deviated from the ubiquitous White Wolf-style experience market, wherein points are like hard cash that you can use to buy your new powers or skills, by introducing the idea of credit. Simply put, you were no longer capped ruthlessly by your acquired memory points, and could “go into memory debt” to buy an ability that you couldn’t yet afford, so long as you paid the difference with the memory yet to accrue. As I recall, the one stipulation to prevent rampant abuse (i.e., players simply giving themselves every ability available and being in “experience hock” forever) was that you had to be able to pay at least one point toward the new skill – you could only get one such ability in experience escrow and couldn’t go into debt if you were already broke or in debt, in other words.
To provide a rough example of how that would work in my own game, all of the skills and assets you have available are treated as fluid by the system (although to you they are fixed). When you need a new trait, you figure out its value and then choose how to acquire it: with experience that you already have, by sacrificing traits already possessed, or by mixing the two. Thus, if you’re a veteran quantum jumper, you have probably built up enough “potential points” and can simply attain a new skill or relationship or whatever, but if you’re really in a bind and low on quantum potential, you can still make the hard choice, letting your existing universe be partially overwritten as a consequence of inviting the new universe in. If you have a little bit of quantum potential, you can mitigate this, and take a lesser consequence instead.
Here’s how I imagine it works: you’re a quantum jumper who needs a bunch of money right away. You cross to a different timeline where you’re quite rich… but you never married your sweetheart and had kids. In the fiction, you’re trying to keep both results, and if you’ve got sufficient quantum potential, you can have both. Let’s say that, mechanically, we’ve defined your relationship at 3 points, and you’re looking for 3 points worth of wealth (to make things easy). Thus, if you have 3 points in quantum potential banked, you pick up the new wealth and return to your marriage as normal. If you have no quantum potential, you could get the wealth, but the reality you acquired it from bleeds back into your own, and you go home to an empty house. If you have a point or two in quantum potential, you might be able to hold onto the marriage and bring back the wealth, but your relationship might be strained, or you may find you didn’t have a child together after all… Obviously, this could work the other way, as well: you might decide to settle for a lower wealth asset if you’re a bit short of potential, so as not to cause destructive resonance back in your own reality.