Here’s a really tiny idea of the type I try to relegate to Twitter, but I just couldn’t smush it into the character limit. So here it is, at languid non-abbreviated length.

Shake it up

Unusual Biochememistry (B160) is a nice disadvantage for alien or other exotic bodies. The effect is simple: standard drugs, if not tailored at high cost for your oddball chemistry, may have the expected effects, or no effect, or expected effects with added bad side effects. Those effects are simple to determine too: there’s just a little 1d6 table with those three outcomes (some imagination required).

There’s nothing wrong with that at all! But some imaginable outcomes won’t pop up, like the combination of zero expected effects plus crazy new side effects. So for a little more unpredictable fun, here’s a replacement that allows for more varied combinations of surprises (maybe even the rare good one!):

Expected effects

First, roll 1d to see whether there’s any change to expected effects and side effects (whether those are good or bad expected effects). Roll once for all expected effects to keep things simple, or roll separately for each expected effect for more detail.

• 1 No effect 
• 2-3 Weakened effect*
• 3-4 Expected effect
• 5 Amplified effect*
• 6 Effect is warped in a weird way*

* Make it up!

Unexpected new effects

Now that expected effects are squared away, roll 1d for unexpected new side effects. If you like, roll once and stop. If you prefer the fun possibility of multiple effects, take any roll other than “No new side effect”, and roll again. Keep piling up multiple new effects until “No new side effect” comes up.

• 1-2 No new side effect
• 3-4 Harmful new side effect*
• 5 Beneficial new side effect*
• 6 Weird new side effect!*

* Make it up!

Harmful effects might be 1d fatigue, or -1 HT, or a -5- or -10-point disadvantage. Beneficial effects should be similarly modest, but could include a couple of Fatigue points, or unexpected Bravery (itself possibly dangerous…), or a small boost to sense rolls. All of these should be temporary, of course!

If you like, combine two harmful or beneficial new side effects into a single, strong harmful or beneficial effect.

Finally, whatever the results of all rolls above, feel free to creatively add “0-point” details just to keep the players worried: a harmless rash, hair standing on end, a barrage of long-forgotten songs coming to mind…

That’s it!

A few notes:

1. It’s nice to have the possibiity of beneficial effects, but note that I’ve made the chance lower than that of harmful effects. After all, this is a disadvantage!
2. Ambitious GMs could create huge tables of possible harmful, beneficial, and weird effects to roll up. Probably not worth the effort – although such tables, along with these Unusual Biochemistry rules overall, could be used any time a normal PC uses alien drugs, or even when rolling a critical result with the use of normal drugs. The system could also be fun when varied Fantasy races, potions, and critical rolls interact (with “weird” taken to mean really, magically weird).
3. These rules replace a single die roll with two or more rolls. It’s a good chance to note that “more rolls” is not always bad! Unusual Biochemistry + odd drug results is anything but a common game occurrence; on the rare occasions the situation pops up, it should be a chance to have fun with scary rolls and surprising outcomes.