A while back, I mentioned a non-essentialist d20 Gamma World campaign as a hypothetical project. It's no longer hypothetical. My d20 RPG Omega World has been published in Polyhedron Magazine. Here's an encounter we had in April during a playtest..
The explorers were camped overnight in a dead forest. During first watch, a strength-draining savage kobold sneaked near the camp to take a look. The PC on watch, a three-armed mutated lizard named Kokbook, missed both his Listen and his Spot check. The kobold sneaked away to find the rest of its band.
On the second watch, eighteen strength-draining kobolds, including an 8th-level leader, surrounded the party. The leader referred to itself as a "king" and waved a broken laser rifle as an oversized scepter. It told the explorers that they were intruding on its land. They were to give it treasure (especially "more guns") or be killed. It had a few normal-looking kobolds with it. The other fifteen were hiding, surrounding the camp.
If the explorers had ever looked into the trees around them, they might have realized they were surrounded, but they never did. Instead, they pretended to offer a Small mutated human ("Tim" or "Tim Tim") to the "king" as a slave. The idea was that Tim could always escape by time slipping into the future, so he wasn't in any real danger. As Tim and Phraint (the mutated insect diplomat) approached, however, so did Kokbook (the mutated lizard, now riding his mutated horse) and Poky (a Large mutated mammal). The approach of the intimidating PCs started freaking the king out, and it ordered them to stop. Instead of stopping, Phraint hit it with Brain Bite. The battle was on.
(Lesson: When one PC wants to be a diplomat and another wants to start a fight, the one who wants to start a fight wins.)
The kobolds won initiative and came out from behind the trees. A few got off attacks, but most just advanced. Tim time-slipped 5 rounds into the future. Kokbook, on his horse, did a ride-by on the king, ending up outside the melee. Poky raged (barbarian-style), cut a kobold in two using his "little" sword (2d6+8 damage vs. 2 hit points), and rolled a big Intimidate check.
The kobolds steered clear of Poky, and they couldn't get to Tim or Kokbook. That meant they all piled on Phraint. Within a few rounds, they'd drained him down to 0 Strength, and he was unconscious. (Touch attacks are the DM's friend.)
Meanwhile, the two best melee fighters, Kokbook and Poky, got to the king and started landing serious damage. (Spirited Charge is a good thing.) As an 8th-level character, this guy had 63 hit points, but they got it down to 20 pretty fast.
At that point, the "king" demonstrated how it had survived long enough to reach 8th level: it ran. In fact, it used its Shaper mutation to adopt a four-legged, hound-like form, and it took off.
Kokbook rode after it, and Poky was right behind. With a few good Ride rolls, Kokbook managed to position himself where he could blast the king twice with the sonic pistol, killing it. (Not having to make an attack roll comes in very handy when you're riding through the woods chasing a little dog-shaped kobold in the dark.)
When the "king" ran, so did the rest of the kobolds, also adopting four-legged "running" forms. But when Poky and Kokbook chased off after the king, that left Phraint's body unguarded. A few of the savages sneaked back to the campsite and started rifling through his stuff.
Suddenly, out of nowhere, Tim reappeared. Only now there were two of them (one from the present and one from 5 rounds ago). Now they were Tim Tim. Tim Tim clashed their spears together and yelled, which was too much for the overwrought kobolds. They ran off into the night.
If I were to do the above encounter over again, I'd play up the "king" angle, like the king would have a toady to introduce him instead of introducing himself.
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kobold: I use humanoids from the Monster Manual as base creature stock, and then give them mutations. In game terms, it's a mutated kobold. In world terms, it's a mutated lizard (or maybe a mutated human).
Phraint: This character was named after the "bugman" from the coolest RPG book ever published.