This isn't wedded or designed for anything in particular. Just some stuff I was ruminating on, and thought it might make an interesting set of mechanics for a game.

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Any time a scene ends, players need to decide how their memories of that scene are dealt with by their characters. Each character has a limited amount of "memory space", and the amount of space a memory takes up is determined by factors such as its importance, related memories (if you take 4 semesters of Quantum Physics, it's easier to remember any of those semesters because you have lots of other things to remind you), and.. probably any other sort of weird tweaky thing players think should matter.

[Tier 4]
Forgotten Memories: Memories from Tier 1 that have been "used up", memories from Tier 2 that have been replaced.

Effects: There might be some kind of threshold where, after a lot of related memories have been either used or replaced, you get some kind of free Tier 2 memory.

[Tier 3]
Keystone/Heart Memory: This is the very lowest, most subconscious tier. Characters can never fully remember these; they remember that they -happened-, and probably even some of the details, but can never fully recall the whole thing, and will never be able to do so much as picture it in their mind.

Effects: Small changes to nearly everything the character thinks or does. Keystone Memories fundamentally change an aspect of the personality, of who the character is, what they want, and so on. Keystone Memories can never be forgotten, and so will never drop into Tier 4. These would give some kind of small bonus to a large number of activites.

Other Uses: Things like racial/genetic memory would probably be put in this tier.

[Tier 2]
Learned Memory: These memories encompass both knoweldge, such as learning how to use a computer, and body memory, as a martial artist might have in relation to his techniques.

Effects: General "skills"? If you just had a firefight and wanted to mark it as a Learned Memory, it might give +2 to Gunfighting or something along those lines. If you remove a Tier 2 memory to make way for something more recent, the old memory goes to Tier 4. Most of a person's "memory space" will be taken up by these.

[Tier 1]
Ephemeral Memory: The thousand things that happen today that you probably won't remember at all in 48 hours.

Effects: These are sort of one-use power ups. You can use an Ephemeral Memory to get a moderate bonus to a tightly-related task: you impersonated the IT guy for the casino earlier today when you were mucking about in the system, and you use that memory now on your hacking test back in your hotel room. Once used, they always drop into Tier 4 and can't usually be recovered.