After 20+ years of Not GM'ing, I was given the chance to lead a three session game, consisting of five player characters, in a setting that I created. The game took place in a mythical land of Guanlong: a magically hidden realm, controlled by an insane Mind Flayer Arcanist. The basic idea was that he would "summon" beings from different worlds, enslaving them, and using them for sustenance, or experimentation.
After being away from gaming for such a long time, I started back up as a player, about seven or eight months ago, playing a Rogue from 5th edition, in a campaign that a friend of mine was game master for. We started playing Tyranny of Dragons, but soon deviated from the path, and kind of went our own way. Some players went on vacation, but some of us didn't and we still wanted to do something, so I offered to GM a short game, to see if I could get back into the swing of leading the game.
I had an idea to read through some pre-written stuff, to make things easier for me, but decided to instead go for some home-brew content, and keep things simple. The story would be more combat oriented, and perhaps have a tad of social interaction thrown in. I really wanted to keep it simple, so that I wouldn't botch this first attempt back with too much to think about. Turns out it was the right decision to make, because I felt that I did a decent job.
I started by choosing a basic setting, something that interested me. I've always loved those old Bruce Lee movies, so I decided to do something asian-flavored. I rifled through the Monster Manual to find something that looked asian, and found that the Gith fit the bill. Along with the Gith, came some other related monsters, such as Grimlocks, Kua-toa's, and the Mind Flayer.
There was a lot more preparation than I had anticipated, and I felt myself thinking an aweful lot about how the game would go, what monsters to choose from, how many, what their stats would be, etc.
In any case, I finally settled on Zombies, Skeletons, Grimlocks, Flesh Golems, and Scarecrows, with the Mind Flayer as boss.
I also had to think about the terrain, because I wanted to give the group some feel of the playing field being more than just a two-dimensional map, so I made them appear on a cliff, and made it possible for them to choose from three different paths: Forest, Swamp, and Desert.
I did have some contingency plans in place, but after the first session, I realized that people are incredibly unpredictable! I learned that the stuff that I want them to do may never ever come up in a game, and so the most important thing would be to present the group with simple situations, rather than any pre-built encounters. Situations, I feel, are easier to come up with, and easier to control how, and when, they come up, and how they flow, overall.
I did find the hardest part of all was the role-playing, and getting into all the different NPC's that come along with the game. Not only do you have to "play" so many different characters, you also have to know what they will say at any given moment, or do at any given time. Perhaps I could have spent more time on creating "situations" for NPC's, and devising a strategy on how to handle the different scenario's that may come up.
All in all, I thought the experience very rewarding, and incredibly entertaining. I found that letting the player's decide their own fate was the key to my success. I presented the party with several situations that would somewhat open, yet still linear enough for me to control. I do think that a one-shot would have been better, rather than a 'short-shot'.
I may or may not GM again, only time will tell, but I will say that it has been a great experience, and one that everyone should try at least once in their role-playing life.