Here's some possible ideas for that approach:
You can find some kind of "coins" in the game. They're semi-rare (or maybe dropped by NPC enemies if there are any) and serve no purpose. You can pick them up, but they do nothing. If you do the lore part, your character will eventually learn that they can be put into that little slot next to these strange devices that are spread all around the map. Putting in a coin will give you a 50% instant-heal. If you have not done the lore part, you can still collect the coins, but they're worthless.On the contrary, if you play in a team and you are fragged (dropping all coins) the adversary gets a big advantage.
You can pray at altars to get a free 50% heal once every 3 mins. The prayer is a random word (either from a random word generator, or from a list of 20-30 words) individual for every player and session, and using the wrong prayer instantly frags you (the gods are angry at you for insulting them, whatever). Doing the "lore part" means solving puzzles until you eventually discover a writing that conveys the healing prayer. If you continue doing the lore, you maybe learn another prayer that will "taint" an altar for 5 minutes, killing anyone who tries to get healed. Or you learn that the altars are really super advanced alien healing devices which are powered from a hidden fusion reactor (so the "god" that the primitives in this jungle pray to is really a fusion reactor). Finding out where the reactor is hidden allows you to destroy it, depriving everybody of their heals. There might even be two "gods" (reactors) and two factions in game, so you can only destroy the one that works for the other faction.
Analogous to the prayer thing, secret passages might open with an individual code word that you must find out. The passage might lead to a weapon/ammo chamber, or simply be a cool shortcut. Or it might lead to an otherwise inaccessible sniper spot.
Edited by samoth, 06 December 2013 - 05:38 AM.