Cool game mechanics to hijack

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Some games, even very broken ones, have very good or interesting mechanics which generate tension or are fun. What I like best about Ylands is that you can use some of those mechanics.

Dungeons of the Unforgiven (5.25 floppy disc) Every step is a possible random encounter. Difficulty increases with depth as does the random loot. Make it back alive with loot. Random heals, if any.

Everquest. 3 linked mobs, each on a 7 (?) minute respawn timer. If you delay the killing of the third one a little, the timers become disjointed and the group spawn can be broken into single spawns. The difficulty of each mob varies, so some spawns can be very tough to break. A time limit is thus placed on combat and you must keep up with the spawn rate if you are going to grind, or kill twice as fast to make forward progress down a tunnel with repeated groups within aggro distance. If they repop behind you,  you die and all your belongings remain on your body until you come get them.

Hurtworld. Everything kills you, first it's the cold, then the heat, radiation, etc. Each zone requires special gear you craft. If you don't have it all, you die if you go in the next zone. The less gear you have, the faster you die. PvP of course. Armed gangs in pickup trucks with lights nightly rampaging through newbie zones was the end game.

Ylands can't do quite all of those things, but enough to use those mechanics to make games. I think that is one of Ylands greatest strengths. Can you think of any other cool game mechanics that might work? I have been messing around with water, using it to flood chambers and chase you along a pathway. I like the idea that you could leap from a cliff and survive only if you cut the water on first and land in it, that type of thing.