Probably the worst issue I have as a Game Master is that I think of a game, I write a campaign plot for it — End, Beginning and Middle, get hyped, hype my players, and after 2 months I get bored with it and want the story to end so I can start running a newer game or campaign I've thought up in the meantime. So I just disappear some weeks and invent I have stuff to do, cancel the game, and run another one.
Usually, midway through our game I have a better idea for a campaign, and that's how our group has evolved: Each campaign, I have to accept, has been more fun and intriguing than the last one, but just the thought I could be roleplaying a better plot with better mechanics is too much. I really like my group, and they like my plots so much they ask me for a Q&A session pretty much every week to know what will happen, villain bios, NPC bios, etc; however I just pretend that I am still enjoying the original campaign.
Two months ago we started playing a 4E game about guys who get trapped inside a videogame, and 4e was very good for it, since it was just fight and fight and fight, and the whole plot is about well, the hostility of the online game towards the players and a moral of "every life is precious", ironic in an intentional way.
The thing is, I discovered 5e, switched systems, loved it, and it doesn't feels like playing inside a videogame anymore. The adventures on that world have become boring for me already, and the players are just coming to the table for the plot. Indeed, I'm supposed to design next adventure but just thinking about all I can do on other setting with these rules hypes me so much, and really, I can't think of anything more interesting for the guys now, specially since we're too deep into the adventure it's too late to make it "non linear".
I'm planning a sandbox campaign for when we "finish" this one, and I'm having fun as a GM as never before, imagining interaction, building the important locations, making random encounter and weather tables, etc; but then I think I have to go back and master something that isn't just interesting for me, may as well just run a pure roleplaying game for the current campaign, no combats, but the players expect more.
When they noticed me making a new campaign, they seemed curious and excited, but one of my friends told me: "We're gonna finish the campaign we have now, right?". She seemed kinda worried the same story would repeat.
My summer break is about to end, and my sandbox campaign design is halfway done, and I haven't mastered our current sessions for days and two of the players even asked me if we could begin the other campaign already, while the other two keep telling me I shouldn't let the current one die.
The fact that there's still too much to do on our current game overwhelms me, since I'm getting bored of bringing them the same story every week, and I already decided my next campaign will be led by player motivations that will affect the little plot I have readied for it, and make them help me build the world.
So, how do I get out of this vicious circle? How do I stick with the campaign in progress and stop being lured by the thought of creating a new campaign?