Using the old Traveller rumours as a starting point, I've created the following tables, which determine the type of rumour, its magnitude, and its level of truth separately. There's still a bit of interpretation to be done by the player/GM, but when combined with another random idea generator (Mythic, Rory's Story cubes, bibliomancy) it should lead to a more satisfying and less certain gaming session.
Whilst I wrote up these tables with Traveller in mind, they are general enough that, mutatis mutandis, they should be adequate for most RPGs, solo or with a GM.
Using the tablesTable 1 determines the general category of rumour, and tables 2-6 specify it further. Table 7 determines the magnitude of the rumour; there are four separate columns, one of which must be selected before rolling. Finally, table 8 determines how true or false the rumour actually is.
To generate a rumour, first roll on table 1 followed by the indicated table 2-6 to determine the general topic of the rumour. Combine this result with a random idea generator to come up with the actual rumour as stated to your character. Some random ideas or rumour types will suggest other rolls on tables 2-6 to come up with something specific. Use whatever combination works to make a good story.
Depending on the rumour you have produced, roll on one of the columns on table 7 to determine the magnitude of the rumour. The Quality column can be used to decide if the rumour is about something good or bad, assuming your random generator result doesn't lean one one way or the other. The Major & Minor columns can similarly be used to determine a positive or negative DM to any concomitant skill checks and the like; these bonuses correspond well to the Major/Minor columns. The plus/minus column is useful to determine DMs & severity if the rumour suggested by the is obviously good or bad. Record all these results, and you're done.
Table 8 should only ever be consulted once your character(s) have followed up on the rumour.
Example: Margaret, captain of the free trader Norland and solitaire adventurer extraordinaire, overhears a rumour in a startown bar. On table 1, her player rolls a 6, Miscellaneous. Rolling on table 6 comes up with 5, business tip. Since she's looking for speculative cargo to trade offworld, her player rolls on the cargo tables in the main rule book and gets Advanced Machine Parts. Margaret is on a high tech world, so advanced machine parts are available locally. Since she is looking for cargo, this rumour will concern another market for them. The tip could relate either to the purchase price here or the selling price at destination. There's an equal likelihood of either, so a die is thrown to decide: selling price. A business tip is likely to be positive, so her player decides to roll on the plus/minus column of table 7 to determine the bonus DM. A roll of 8 results in a +3 DM for sales. Margaret has heard the following rumour: "I hear that factories on Delaford VII are in desperate need of advanced machine parts. I know a guy who made a killing selling 50t of them there." Margaret's player records the rumour, and notes the +3 sale DM. If she takes a cargo of advanced machine parts to Delaford VII to sell, a roll on the truth table will be called for. A roll of 10 (mostly true) would result in a +2 sale DM. A roll of 6 (mostly false) would mean there's no bonus DM at all, whereas a roll of 4 (completely false) might call for a roll on the plus/minus column to determine a DM penalty for sales. A roll of 2 might indicate that importing machine parts to this planet is a capital offence. It's possible that Margaret could use Investigation or some other skill to determine whether or not the rumour was true, but a business tip like this won't necessarily last long enough for her to find out before it's gone.
Asking an NPCIf an NPC is asked a direct question about a specified topic (including, "What do you know about...") the rumour tables can be used to help determine their answer.
It will be necessary to first determine whether or not the NPC knows anything at all about the subject. If it's not obvious, decide a chance in 6 they would have some knowledge, and roll a die.
Next, if you haven't already done so, make a Reaction roll for the NPC, applying any pertinent modifiers. If you're using an RPG without a reacton table, roll a simple 2d6, with 2 being hatred, 12 being friendship, and 7 being neutral. Make a note of this reaction, as it will be needed during the Truth step.
Use your random idea generator(s) and any necessary rumour tables to determine the nature of the rumour as normal.
If the NPC's reaction roll was 9 or better, they will not only relate the rumour but give you an honest opinion about it. This allows you to roll one of the Truth dice immediately. Make a note of this roll; when it comes time to determine the Truth of the rumour, you've only one die left to roll.
d6 rumour type
2 background (table 2)
3 fact (table 3)
4 library data (table 4)
5 location data (table 5)
6 miscellaneous (table 6)
* If nothing is currently being investigated, treat as 2, background. Base throw of 8+ to detect the clue; use table 7 to increase/decrease the difficulty. )
Table 2 - Background
d6 backgound of...
Table 3 - Fact
4 technology (or magic)*
*Sci-fi setting: 1 in 6 chance to be about Psionics
Fantasy setting: this will normally be about magic. 1 in 6 chance to be about mundane technology
Horror setting: 50/50 for either
Table 4 - Library Data
*only 1 in 6 chance to require a truth roll; if no truth is necessary, roll on the plus/minus column to determine its value (which may give a bonus/penalty to an etiquette roll or the like). Roll a d6 whenyour character tries to useit to impress: 1-3=bonus, 4-6=penalty.
Library data can be any form of the written word (possibly other media in high-tech settings): book, play, poem, public inscription, datatapes, etc.
Table 5 - Location Data
1 specific location single room
2 vicinity specific location
3 city vicinity
4 region city
5 planet region
6 system nation
Table 6 - Miscellaneous
1 recommendation to action
5 business tip
6 potential patron
Table 7 - Magnitude
2d6 quality - major | quality - minor | plus/minus
2 certain death -5 | difficulty -2 | ±0 neutral
3 ruin -4 | difficulty -2 | ±1 aid/annoyance
4 disaster -3 | annoyance -1 | ±1 aid/annoyance
5 difficulty -2 | annoyance -1 | ±2 benefit/difficulty
6 annoyance -1 | neutral 0 | ±2 benefit/difficulty
7 neutral 0 | neutral 0 | ±2 benefit/difficulty
8 aid +1 | neutral 0 | ±3 gain/disaster
9 benefit +2 | aid +1 | ±3 gain/disaster
10 gain +3 | aid +1 | ±4 good fortune/ruin
11 good fortune +4 | benefit +2 | ±4 good fortune/ruin
12 miracle +5 | benefit +2 | ±5 miracle/certain death
Table 7 notes: If major/minor is uncertain, roll 1d6: 1-2 major, 3-6 minor. If the rumour could be either good or bad, use quality and the corresponding major/minor. If the quality is obviously good or bad, use the plus/minus column to determine the degree of goodness/badness.
Conversions: If using a d20 system, use the Major modifiers for Minor ones, and double this for Major. For a d% system, do the same and multiply by 5.
Table 8 - Truth
2 deliberately false - trap
3 completely false
4 completely false
5 deliberately false - annoyance
6 mostly false
7 mostly false
8 partly true
9 mostly true
10 mostly true
11 completely true
12 completely true
Table 8 notes:
Library data: DM +1d6 if unfamiliar source, +5 if known and trusted source.
Reaction modifiers: If the classic Traveller reaction table is being used, DM +1 if reaction roll was 10+, -1 if reaction 6-7, -2 if below 6.