(This was before I knew about Patrick Stuart's underdark project)
Possible stats for light sources:
- After a number of turns you make duration checks to see if your light source extinguish. This way you don't know exactly how many turns your light source will last. Maybe the duration check start at 5 or under on a d6 and lower by a point each turn (or each time you fail). The quality of the light source may influence the type of die you roll or the starting chance of duration.
- Light sources have saving throws to resist being extinguished.
- Light sources flicker during combat and light a random radius.
What can diminish or extinguish your light sources?
- Melee hits
- Dropping your light source (or falling with it)
- Magic and supernatural effects.
- The referee show the monsters numbers and hit points and can mention their stats.
Effect of light on monsters.
- Attract or repulse them.
- Influence their behaviors.
- Boost, weaken or debuff them.
- Hurt or heal them.
- Activate or deactivate their special abilities.
- Mutate and transform them.
- The referee hide his or her dice rolls and the monsters hit points and stats (and everything that you can hide).
- Players can't consult their map, books, etc.
- Augment the chances of fumble and remove the chances of critical hits.
- Lower the henchmen morale.
- If the group have completely lost their light sources: roll on a lost in darkness table.
Flora and Fauna:
- Light plants attract type A predators but repulse type B predators.
- Light plants provide light for lightless plants & creatures. Become ecosystem.
- Mobile light fruits.
- Dark plants close when exposed to light.
- Fishing monsters or plants that grab light sources with roots or tendrils.
- Light and dark spores that react to light sources.
- On/off bioluminescent creature.
- Taggers that spit bioluminescent goo.
- Creature that glow more as it is damaged.
- Creatures that split or grow when exposed to light.
- Bioluminescent creatures that are super friendly in the dark but who turn frenzy or evil when exposed to light.
- Creatures that blink (like a blink dog) when exposed to light.
- Creature that travel/jump through light sources. And that can end up in your eyes.
- Magic lights that lay their eggs within artificial sources of light.
- Light vampires that feed by draining light.
- Glow worm wizards.