[Discussion] Using two games systems in one game

So I had this idea for a while but I'm unsure how to implement it. I want to run or play in a game where there are two worlds. Unsure of the exact details, but one would be the 'mundane' and one would be the 'magical' world. Now mundane does not necessarily mean it has to be the real world, just that it would be the "default" from the PCs perspective. It wouldn't have magic (or not a lot of it) and not a lot more than what is needed for the conceit of the setting. Then the magical world would be just bonkers with magic or what not.

The question is, what two systems could I use to run such a game? I want them to compliment each other but not be exactly the same. The story would have elements bleed over and take place in both worlds. Like if the magical world was a generic fantasy setting, killing a dragon might result in the death of a company CEO or a drop in their stock, or even closure.

Pcs would change races and abilities. All that the other world has to offer.

So any ideas?

Maybe you could use Fate, but with completely distinct skills, stunts and extras, for the two worlds.

The main advantage for that would be the seamless transition between realities and mostly the same ruleset for your group to learn. What do you think?

I'd stick with two relatively simple systems. Two flavors of Powered by the Apocalypse (one for each version of the world). I feel like there's a favor of PbtA that actually has your concept as the basis for it. Heartbreakers, maybe?? Additionally, I think Trinity Continuum: Anima uses the conceit of using a real world and an MMO that interacts with it.

Outside if that, Fabula Ultima or Infinity's Edge would be great, simple systems to run the general fantasy part of your dual game. Both are great, simple & easy systems to learn and run.

Back in the 90s I ran a long Spacemaster campaign (super crunchy). As part of t it, the characters had a virtual reality machine and would occasionally plug in during a long interstellar voyage. So I'd hand them new character sheets. "It's Earth 1850, the wild west. And your werewolves. Go."

Worked just fine, mixing the systems that way. Character personality remains, the stats and rule systems different.

This was one idea I had. I thought about using Fate Core for the mundane, then Accelerated for the magical. It would be no bog deal to drop a magic sword back in the mundane that way, but it didn't feel different enough. I suppose I could research more modifications to implement the feel I'm going for.
I do like PbtA and could see some of that working, but I don't know that I've read Heartbreakers. I'll look into it. I feel like I saw a system called Anima once and enjoyed the anime style it proposed. That could be one side of things if I'm thinking the same thing. I remember a "build your own" feel with points to buy abilities? The other twoxare completely unknown to me but I will look into that
This is kind of what I was going for but I want the two worlds to bleed ack into each other. So smashing two systems together for certain chapters isn't quite what I want.

But it's given me things to think on. Still open to suggestions.

Alright, this is an interesting premise.

If it were me... I'd let the magical world be D&D 5E (2014). For the mundane world, I'd run Everyday Heroes.

Everyday Heroes has its strengths and weaknesses, but in this instance it benefits from being a modern d20 system using 5E framework. The rules are close enough to D&D that you could reasonably overlap the two without too much effort.

I have done this on a few occasions. I found that, unless the whole group is really into trying lots of different systems, it is best to try use the same system for both (or at least the same basic ruleset and resolution mechanisms).

I have used one system and had the players make different characters in each world (sometimes more than one). I have also had them make a primary character, but bolted on relevant 'magic' systems to that base character for each world they go to. They only have access to the stat/attribute that powers that magic (or hacking, or whatever) when in that type of world.

I have also had them interpret what their stats mean differently in the different worlds, going with more generic or even obscure names for their stats can help: Strength/Intelligence/Constitution tend to be a bit hard to reinterpret, but Insight/Prowess/Resolve are much more free to be interpreted any way we like, names matter. :) (When I roll my own I often go with simple names like Body/Charm/Wits (with an optional Magic stat if needed).)

This might just be my —ever-increasing— preference for simple systems that get out of our way and let us play, but this sort of complex and varied setup begs for a light system (World of Dungeons - Breakers seems like a good basis to start from, and has an inherent assumption of multiple worlds that play by different rules). Any system that is generic enough to not impose its own type of world is a good candidate.

I see the logic behind keeping both worlds in the same system. One inspiration for this idea was the old D&D cartoon. I felt like there was an episode where the kids got home but the Venger started taking over and they saw that so they decided to go back and help.

It would be simple to strip down the mundane characters or use that Everyday Heroes suggestion and let them add features as they level up.

But I felt like part of the fun would be having two different rules sets. The mechanics would make the two characters per player feel different.

I think two different rulesets (as long as neither are particularly crunchy) would probably be a good call. It'd really differentiate the two different realities, though it would be difficult to do a crossover like the Venger/modern world example you mentioned. Great episode, btw.

This is how I've run similar concepts in the past. One system can disappear into the background and not let the process of switching mechanics grind the game to a halt or cause confusion.

I usually use Cortex as my base, and switch to different trait sets based on which world they're in. My multiverse world had realities collapsing in on each other, and characters could try to save their multiversal counterparts or absorb their powers if they could not be saved. It worked really well with Cortex as combining different trait sets in the modular system give gameplay a different feel by design.

That sounds interesting too.

End of the day, if you have buy in from your players, switching it up is also a great way to try new systems. In the 90s we did a time travel game where we basically traveled to the future of the Traveler game, or the Cthulu 20s, or the Space 1889 Mars setting, or whatever game we wanted to play. We did our best to recreate our characters in the new system, but it gave us an excuse to get into action right away and try a bunch of systems.

It just comes down to what you're trying to accomplish. If it's about the setting and the story, one comprehensive ruleset might be better, so it gets out of your way. If it's about a vastly different feel to each section of the game, two rulesets could give you that. Heck, Lancer is basically two games in one for that exact reason - mech combat is different from the interpersonal drama of the mech pilots.

I don't know Lancer at all, but that could be the kind of thing I'm looking for. I eventually want the whole story to be action, but the mundane world would start more limited. You don't run around with a sword kicking in doors and looting treasure vaults. Whether the setting is 'real-world adjacent' or 'cyberpunk corpo dystopia' the mundane would be about investigating the mystery in the beginning. As time moved forward PCs would gain access to abilities in both worlds.

I'll have to look into that idea.

If you want a wild one, check out Vurt for Cypher System. It's all about a futuristic Manchester in which you can lick drugged feathers to enter a mutual dream world, and it bleeds back into the real world. It's very Mature (and immature at the same time). The book it's based on is bonkers.

Hmmm...ok. that also has promise. I hadn't considered Cypher. I could ask players to make mundane characters from one limited set of traits, and the magical world could have a wider selection, and as time goes by I can give them access to the different options they picked in each world. It wouldn't be the two systems exactly...but what they can do with their actions can be very different.

This kind of goes back to the Everyday Heroes suggestion. Which I've never looked at, bit I have seen the Cypeher book that contains multiple genre options, so that may have sparked something now.

Still more contemplating to do.

If you're considering Cypher System the look at The Strange. It's literally about hopping between pocket universes and your characters are translated in the crossing. So a police officer in modern earth might become a holy warrior in Ardeyn (fantasy world) or a gene splicer doctor in Ruk (biopunk future dystopia).