Unique Game Mechanics

I've started generally getting a feel for DMing D&D 3.5ish (meaning I've seen things other places that I like and use them too).  But I was wondering if anyone had any cool mechanics, or ideas, that they wanted to post here.

Moved to Off-Topic - Gauss

instead of roll 1d20 for resolution, roll 3d6 instead. instead of 1d20, roll 3d20k2dh1, which stands for roll 3 and take the middle, this bellcurves out the randomness nicely. and also I recommend <a href="http://www.d20herosrd.com" rel="nofollow">www.d20herosrd.com</a> but I am super interested in Mutants and Masterminds Third Edition.

I had fun DMing a low-level adventure in a tidal cave (before easy access to water breathing).&nbsp; With a 20ft variation between high tide and low tide, sometimes the party was trapped in an inner chamber until the water went down.&nbsp; The level of the water affected what they could see (like that hidden crawl-height passage near the floor) and how easy it was to fight monsters (neck-high water?&nbsp; Underwater fighting penalties if you don't have free movement ). One of my players also really enjoyed a "test" that I gave them.&nbsp; They needed help from a druid, and on the way to find them, they came across three (rule of three!) situations that could be resolved in one of two ways.&nbsp; Depending on how they chose to resolve them, and how that resolution aligned with the tenets of the druid's patron deity, the attitude of that druid (who was watching from the shadows in bear form, of course) would be affected.&nbsp; (eg - they're really hungry, and come across a wounded rabbit.&nbsp; Killing and eating this rabbit is okay.&nbsp; Coming across a healthy but trapped rabbit, though - that rabbit should be released.) This party has a compass that points the way to the BBEG lich's phylactery, but every time they open it, the BBEG can send to them, knows where they are, and is able to direct undead to their location.&nbsp; Risk/reward items are pretty cool, and this one is helpful at railroading the party back to your planned plot, without it feeling _too much_ like railroading. At very low level (1 or 2), I had the party's cleric kidnapped by a band of kobolds while he stood watch.&nbsp; They woke up in time to see him disappear through a secret trapdoor in the floor of the ruined barn in which they were sleeping.&nbsp; They then had to navigate the kobold's trapped den and rescue him without any access to healing or buffing.&nbsp; Denying the party their primary playstyle (in this case, rush in, hack, slash, and then heal up) causes them to think creatively and change their approach.&nbsp; If you've got a party that relies on heavy magic use, let them encounter an antimagic field, or silence their caster.&nbsp; Regenerating monsters are fun, too, as they try to figure out what the monster is vulnerable to, and how on earth they can apply that type of damage. BTW - I'm new-ish to D&amp;D, and to DM'ing, so all of the old cliches, and the tried-and-true tropes are still new and exciting to me :)

David, your games sounded awesome and inventive. As long as you and your players are having fun and enjoying the games then you are doing a good job.

Nothing more fun than finding out a regenerating monster is vulnerable to bludgeoning damage, then proceeding to coup-de-grace them for several rounds with a chair :)