Started a Homebrew (first DM ever) and I could REALLY use some help!

So, I started my own idea for a campaign, and I the players seemed to really like the idea.  We're a time/dimension traveling agency hopping back and forth to save important heroes because cataclysm is imminent and reality is coming apart with adventurers and heroes having become so scarce.  The idea is, we're a group trying to find the right way to intervene in situations where there was a total party wipe and stop that from happening so they can continue in their adventures. 

I have some imagination, but not as much as I'd like.  Do you guys have any suggestions or past experiences on fun, crazy, or harsh experiences in campaigns where things took a bad turn?  And if possible if you could include some vague details on what classes, levels, enemies we're involved and the setting it would be greatly appreciated... and the motive for the party to have been there.  Thanks.

Have the players actions in the past come back to screw them over in the future.  For example, save someone that starts an organization that starts out good and eventually turn to evil.

And/or do the reverse - have a friend they meet later originally be an enemy and their actions turned him friendly.

Have a blatant paradox that is unexplained.  Wait a second, how can we kill George when we know he is alive later?????

Have some people be really mad at the party in the future, but they do not know why until they go back in time and screw over that guy.

I was in a similar adventure once, where a dragon broke loose in a time-traveling organization we were part of and killed everyone except for the modrone operator of the time machine. We then traveled to some other planes and eventually Eberron, where we were at first trying to kill some Yuan-ti and take their cargo until the former, now dead leader of the organization popped up and tried to take the cargo - the egg of the dragon that massacred the headquarters of our organization. It was a pretty good twist. 

I would recommend doing something like that. Make people not as they seem, and have the characters fight the past or future version of those people. They then go back to the present and confront the person. Drop backstory of things that have already happened in the timeline into the past, and the impact of things currently happening in the future. Play into the funky nature of the time/dimension-jumping nature.

I ran a short campaign like this once. In that campaign, the reason for reality coming apart was an angry time dragon. The dragon had been captured by an evil wizard (how original, wow) to harness it's power. That was fun, if not slightly unoriginal but it is something to think about as a potential reason for what is going on.

Time loops need to be closed - be prepared to retcon almost anything, and tell the players as little as possible.

In the above example, where they see George die, but for the last 7 sessions George has been alive in the future, you as the DM will need to work out why that is. Did George come back to life? Were there two Georges? Is George actually a doppelganger? Is the doppelganger friendly, or evil? Is George a construct? Does George experience groundhog day, and when he dies, he wakes up in the morning?

I would recommend playing fast and loose with the plot. >Someone< is up to no good, and that will be revealed later depending on who is still alive or still present. You need to decide what they are doing and how it progresses, and decide who it is based on who's left when it's time for the reveal!

Remember. The characters actions have consequences. 😏

Go of the time travel rules from most books (I’ll use Harry Potter)

if they mess with their past self’s the action affects them

The crisis needn't come from time travel, per se (even if your party has). What if your villain is normally a decent enough chap, but has decided your party is his problem which must be eliminated? Like, he cast a prophecy which portends doomsday and a subsequent reading of his Tarokka Deck names your adventurers as the perpetrators who will bring about his ruin. So now your players must do something (like conquer his world) if only to save their skins long enough to convince everyone they are harmless. Or what-have you.

Just a thought…

Have you ever played any time traveling games, like Journey Man project?   For the format you want, you have to determine two things for every mission.

A. The outcome you're trying to prevent.

B. What time traveling rules are you imposing on the party?

This whole frame work is the foundation for creating a puzzle the players must solve, not by exact solution, but by meeting certain criteria.  How much information do you provide them ahead of time?  How much do they need to discover during the outing?  Are you using Ground Hog day rules (as many retries as needed)?  Give each varying tools to help them solve problems... especially to avoid notice.  

Also... is there gonna be a big twist where the reason all the heroes became scare is because the party was interfering with things?

I still haven't been able to start this campaign.  Turns out one of the other people in the group wanted to start a game too, so we're playing a bunch of thieves trying to make our way up in the guild ranks.  But I am still wanting to do this campaign in the future... probably much further into the future;).  I like the ideas here though thanks! 

I am definitely going to gave some personal bond shenanigans going on... like if they have a teacher in their backstory that means alot to them, they find out that the great loss their teacher suffered that drove them to become what they are was the party's fault.  Or they meet what they think is a villain to destroy, eventually time travel back to meet an earlier version of them that they actually like and then give them the option to try and intervene... on themselves lol (they may have to fight their own selves from the earlier fight and find a way to beat them... I think this would be a fun way to introduce the "anything you can do I can do too" meme, but it makes sense, because its ACTUALLY them;).  

Cheers for the ideas!

Oooohhh. This sounds so awesome! I love it. Some advice for first time DMs and making a home-brew campaign:

1. Read published adventures. Even in a home-brew campaign, its good to read published adventures to understand the structure of an adventure, and get more ideas!

2. Don't plan out the entire campaign at once. It's good to make a simple timeline to help guide events, but your players will always throw a curveball at some point, so it's good to not have an entire session planned that ends up never being used, this is both a waste of time and just disheartening. I have learned this the hard way :)

3. Have confidence in yourself. Dont constantly worry about what could go wrong, and just go with the flow. Here's a tip from personal experience: Don't constantly worry about if your campaign is good, and don't keep asking your players if they are having fun. If they aren't, they will tell you.. 

4. Have fun. You deserve to have fun too. Make an experience  that is both fun for you and your players. 

5. Be honest. If youre stuck, not in the mood, or just worrying about something, tell your players! They will understand.

Hope this was helpful,

ChildOfStardust

Thanks, appreciate the advice.  Yeah I sort of had an eye-opening experience when I tried to do an impromptu one-shot simple adventure for my kids and their friends.  I introduced this cool Scooby-Doo like haunting hook that they're investigating.  They arrive at the house, and then instead of going inside the house, they opt to go up to the roof because I made a random mention of gargoyle statues up there.  And then they went to the backyard. 

They got bored, I wasn't sure what to do to make the roof and garden interesting for them except have the statues be like weeping angels, and them getting snagged by living vines... Apparently that wasn't interesting enough.  So that does make me worry that if my adult group goes off the narrative and story I have planned that I may not be spontaneous enough or know enough about D&D innately to respond to things off the cuff.  I guess that's why DMs usually show to games with a whole laptop or several giant binders worth of information at their disposal hey?