First time I did it was with Zelda: A Link to the Past. I beat that game every way I could imagine. Beat it with no bonus heart containers. Beat it without armor upgrades. Beat it in one sitting with no continues/deaths. Beat it without any bottles but the one you have to get for a quest, but didn't use medicine or a fairy in it. Etc, etc. I loved coming up with different challenges to do in that game.

I've done it with a lot of games over the years, but that's the one I think I did that the most with.

City of Heroes. My main in that game was a tanker with Super Jump as his main way of getting around. I spent 50% of my time just climbing skyscrapers with super jump, getting as high as possible if not to the top of a building. And then I'd jump to my doom. could you even jump to your doom in that game? It might have been percentage based damages from falls at that point.

First time I did something like that was Starflight way back when. Sure there was a plot, and the clock was ticking down toward universal destruction, but screw it, I wanted to go exploring and mining!

Ok, hmm the first vivid gaming memory of doing this was Intellivision Auto Racing where I went against what the developers had really designed the game to be. It was a 2d top-down lap-based racer, BUT you could drive off the course. If you drove carefully you could get between trees and houses outside of the race course. I was always terribly curious where I could get if I drove carefully enough not to crash into the scenery. There was this whole self-invented sidegame around finding paths that wouldnt result in a dead-end. If I remember right, once you crashed into anything surrounding the course, you would spin around until your car returned to the track.

I never got too far, but I enjoyed this exploration more than the normal game racing itself.

Maybe in the more developer friendly definition of emergent gameplay, Intellivision also gave me Sea Battle, where I could battle against the AI, preferrably as a sub.

I think it was called F-17 Stealth Fighter on the Commodore 64. It was a flight sim by Microprose if I recall correctly. After having run a few hundred missions I finally got tired of playing it by the book. Toward the end I was going on missions trying to set off as many warnings as I could while sustaining as much damage as possible while still being able to complete the mission and land safely. I always got such a rush landing my bird on a carrier when everything in the cockpit is screaming I should've ejected 30 minutes ago.

Yup. That's the exact game I was thinking of before I even opened the thread.

My brother and I totally played that "game" too! Far out. Man I loved that title.

Probably Quarantine. The ability to ride around city and kill pedestrians (that was before Carmageddon) was enough. No need to take up missions. Well, there is, when you want to eject passengers from the backseat right at the wall you are standing next to... In my defense: I was probably 14.

Top Gear
Top Gear was a typical SNES racing game - first to the finish line wins. It had split screen 2-player, so my brothers and I would play cop and robber chase. Someone would be the robber and get an X-second head start, then the cop would try to catch him by bumping his car into the road shoulder. We didn't care about finishing the races or being passed by all of the AI cars.

Mortal Kombat
Also on the SNES, we split everyone into teams. One person from each team would grab a controller and randomly choose a character. Then the players turned their backs to the TV. All of the other teammates would be responsible to telling the players what to do - specifically, what button combinations to press, and when. No one was allowed to say which character you got. Only yell buttons and timing. The action on-screen ranged from hilariously awful (both players facing away from each other punching air) to surprisingly coordinated with combos and the like. This is more of a creative way to play rather than emergent gaming, but I wanted to share it anyway.

Star Wars Galaxies
MuhMorPuhGuhs don't quite qualify since they're designed to support at least a few gameplay styles. I got the most joy out of hunting those giant turtle monsters with my Wookiee. I became so good at it that I could almost sniff out their spawning areas, even on planets I wasn't familiar with (and I explored a lot of places looking for them). I also had a trapping/attacking method that was very specific to their speed and size.

Battlefield 2
When my mates are I got bored defending we started playing Explosive Barrel Russian Roulette. The group would takes turns, one at a time, standing on an explosive barrel or fuel tank and putting one bullet (pistol or rifle) into it. It was never easy to calculate how much damage they could withstand - or the specific damages from the various guns - so it there was always a moment of wincing as you clicked the mouse button. Inevitably someone has to fire the final bullet and gets blown way the hell up the air. BF2's ragdoll effects (and death sounds) make it funny every time. Eventually, if we were drinking, we'd forget about the battle altogether.

I have ton of additional examples but those are some of the stand-outs. I never knew the name for it, but I really am an emergent gaming connoisseur - to the point where I might, all things considered, do more emergent stuff than actually playing by the rules/storyline.

WoW: With my mage, I'd make up small challenges to see if I could figure out how to solo them. My favorite was taking down an elite level 45 dragon at level 40.

GTA: Does it count if I just ignored the missions and randomly killed people for money?

Homeworld: There's a level where you have to sneak into a very well defended base... it's being defended by a very large sphere of ion frigates. I once spent a couple hours seeing just how many of those frigates I could steal. I took about a quarter of them before becoming bored (probably around 50-75).

On the ancient Colecovision console, it was possible to kind of half-insert a cartridge and have it still work, albeit with screwed-up graphics and tons of glitches. I spent a lot of time doing just that, trying to play all the way through Donkey Kong Jr., Zaxxon and the like while barely able to see what was going on.

I must have been one bored kid.

Myth. I can't count the number of things I did in that game that weren't directly related to the game. From dwarven golfing, fetch lightning art, to simply stacking powder bags and wights to get the biggest boom and funniest bounce of weaponry. Or "how many thrall can I hide under this body of water?" I remember when the fetch lightning distance glitch was discovered and I practiced for hours mastering it so I could rain death on my helpless friend from across the map and he couldn't figure out what the hell was going on. "Oopsie, there went your soulless! Oh dear, was that a wight in the midst of your troops?"

I doubt that this was my first such experience, but the longest term one for me was in GTA 3. After I reached a certain point, just after the 3rd area was unlocked, I lost interest in the game itself, and just played Murder Survivial Rampage.

From the garage in the first area, chuck some grenades up the ramp. Blow up at least 3 cars. Creating a traffic jam first was always good. Cops soon follow. Snipe until a helicopter arrives, and then rocket it to oblivion.

By this point, wanted should be up to max. A choice then arises; in one half of the garage, a Banshee. In the other, a Barracks. Either see how many time you can make it round the block, or get into the barracks and see how long you can last driving.

This spawned countless drinking games, competitions, bets and other silliness when I was at Uni for the second time. I never did see the end of that game.

Ooh, Oddjob hide and seek in Goldeneye. Simple as it sounds. That was Uni the first time.

My friend and I used to run time trials through a leaked demo of Redneck Rampage that we downloaded.

I think my best time was just under 45 seconds.

Halo

Going through the whole game using only melee attack. Taking out the dudes with swords was a bit tricky...

Okay, you are to be awed! I loved F-19 Stealth Fighter. I played the way you described as well as the "usual" way. I remember when I won the Medal of Honor, man what an experience! Thanks for the trip down memory lane!