Karma rule for RPGs

 Karma

Every time a d20 is rolled for combat, saving throws, or skill checks, roll a d12 Karma die alongside it. This includes monster/NPC attacks.  Regardless of the outcome of the d20, apply the Karma result to the player character.

12: Something good for the PC happens. This could be anything appropriate to the situation. DM fiat, but occasionally offering the player a choice can be entertaining. (Would you like advantage on your attack next turn, or advantage on the damage roll right now?)  (Monster hits, but falls prone.  You hit the monster, causing it to drop its weapon.  You unlock and open the door just in time to see the guard leave his post to go use the toilet.  The guard catches you sneaking into the store room, but just nods and mutters "A bottle of wine from the top shelf, and I didn't see anything.")

1: Something bad for the PC happens. This could be anything appropriate to the situation. DM fiat. (PC gets disadvantage, monster gets advantage, drop a weapon, armor or weapon is damaged, break a tool, jam a lock, attract unwanted attention, wandering monster arrives, monster attack cuts off coin purse, the seduction attempt works way too well and you gain a stalker or STD, your dagger gets stuck in the monster, etc.)

A Blessing can increase the "something good" to a roll of 11-12. Blessings can stack to a max of 9-12, but must be from separate sources. Blessings last until removed (however that may happen). Don't annoy the priest!
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A Curse can increase the "something bad" to a roll of 1-2. Curses can stack to a max of 1-4, but must be from separate sources. Curses last until removed (however that may happen). Be careful striking down a witch - only she may know how to remove that curse!

A character can be both cursed and blessed. They do not offset each other.

Cursed or blessed magic items like a pet rock or lucky socks are entertaining. It's even more entertaining if the item has some condition (petting the rock for 5 minutes, not washing the socks) to enable the karmic increase. It's possible for an item to bestow either a blessing or a curse, depending on how the player/PC treats it. (A depressed or angry pet rock is a terrible burden, especially if you try to abandon it.)

As a further option for role playing, roll Karma at dawn each day. That is how the PC's day is going to go. Some days, it just doesn't pay to get out of the bedroll. Some days, opportunities just seem to fall into your lap.