Characters accumulate experience for activities that they perform which either should improve the character`s skill at doing something, or which we want to encourage to make the game more fun. Experience improves a character`s skill at performing some activity, thus making the character more powerful. Experience comes in two types: skill experience (SXP) or generic experience (GXP). Skill experience is only applicable to the skill for which it is intended. Generic experience can be spent on any skill that the character chooses, and possibly on other special actions.

We use a `tank and drain` model for XP of both sorts. Each character has a tank in which he accumulates experience. An experience packet is put into the tank at the top of the tank. Each experience packet knows how much XP is in it, whether it`s GXP or SXP, and, if SXP, to which skill it applies. The tank has a certain size in experience points, and if the packet has too many experience points to fit in the tank, enough points are lopped off to make it fit. When your XP tank is full, your character will get a message telling him that he can`t learn anything more for a while. When your tank is empty, your character will get a message telling him that he is hungry for new experiences.

Points in the tank aren`t usable yet. At the bottom of the tank is a drain, from which XP is pulled and used at a specific rate. So, whatever XP packet is at the bottom of the tank has an amount of experience drained from it every so often until it is gone, then we start in on the next packet. When the experience is pulled from the drain at the bottom of the tank, it gets used. For SXP, the experience is directly applied to a skill. For GXP, the experience is put into a pool, and the character may then explicitly assign it to whatever skill they like later.

Each skill also has an experience tank and can absorb new experience at a particular rate. Some skills will also have threshholds in their lifecycle where you will need a piece of lore to improve it further. When this happens the skill tank backs up until you obtain the lore, then the experience floods in to match where you would be had you possessed the lore the entire time. This is akin to being taught something, but not fully understanding it. Then when you get the missing knowledge, all of the sudden your experience "makes sense" and you are off and running.

The rate of drain from the tank increases significantly under some circumstances. If you are in a tavern, your rate of drain is doubled. So, when you get that message telling you that your brain is full (the dread BIF message ;) head on back to the bar and shoot the bull with your buddies. Who knows, while you`re there you may get a lead on your next great adventure