What should we be aware/cautious of when hacking together these systems? [closed]

Question

We've talked new games and settings, what we like and those we found awkward.

We haven't played all of the following together, we have a diversity of experience so I can rely on the opinions of others for what worked and what was a problem. Here's a list of those games our group have played: D&D, Pathfinder, Ars Magica, Fate core, Wraith oblivion, Mouse Guard, The Riddle of Steel, The Burning wheel.

We want to try to have it all, to choose the best of the 'neglected' rest, and make a real witches' brew.

We want more player influence in the story development, but more realism more real history (low fantasy). We love the Esoterrorists themes for its Lovecraftian magic, and the precarious membrane between the worlds. I've never played Ars Magica but by report the medieval setting looks amazing (I think we'll lose its magic system mechanically but retain loads of flavor and perhaps the troupe). We've played Wraith as a group and loved it so we'll have some of the setting ideas there and the low power magic.

In terms of mechanics this is what we have (we pooled our resources and together we have game books for all the above).

We are thinking of making a setting like Lovecraft's dreamlands with the mutability of the Deadlands from Wraith and have the players move between worlds tracking down medieval Esocultists.

My obsession is the little played The Riddle of Steel for its cool combat system. I've translated the target numbers to obstacle to make TRoS a bit faster (much like was done a bit from TRoS to the Blade of the Iron Crown). We're changing injury to wound levels and conditions TBW style. Turned the maneuvers into cards with pictures and summary of such.

Em loves The burning wheel for its style of testing all of them and it power of resolution, resolving action a various levels of granularity (perhaps also retaining other stuff but not their fight system or the three volley exchange).

We've played Fate and we like it but super powered cooperation is an obvious issue, it gets very messy, so we want just a sprinkle to allow us to add skills beliefs instincts traits and wises on the fly, while limiting this and their operation to Burning Wheel rules. This way we get off the ground quickly and get the players to rp their characters. Aspects and fate points to cover the TRoS Terrain stuff and of course cool shit that people want to do, for which no rules exist. Compels to democratize the play, and to let me complicate players lives, limited by the Artha economy. I've got The Burning Wheel gold edition for an eye to balancing aspects, matching to traits etc. and for progression and testing.

As a GM I still want to use maps and use tokens. The minigame of positioning and cover is much of what we all agree we liked about D&D. To be honest theater of the mind is just confusing, and while The Burning Wheel has interesting mechanics for dealing with this it's too much of a culture shock for me atm and I still want to make maps.

The Burning Wheel advancement with Skills, Beliefs, instincts and traits seem very like TRoS, so I can work with those.

Conclusions Most of these games have a pool dice mechanic I've chosen a pool of d12s to made the math/conversion of mechanics easier, but no doubt the balance will take some time to shake out.

The big hole in our game atm is our magic system (we'll probably go TWB and use some kind of collective willpower checks and have magic in the dreamlands but not the real world without weakening the membrane.) I see if we can adapt something of wraith in there somewhere, but it's just more work.

If anyone out there has done this and has words of warning or helpful modifications that I should consider or features to avoid I will feed it forward.

Answer 1

Combining parts of different systems and worlds into something that feels right and works for you can be very rewarding, but tends to include some pitfalls that can lead to in-group friction.

Unintended consequences

Some synergetic effects can arise - "cover" provided by the combat positioning system can mean something else in the magic system, for instance. These kinds of issues tend to remain unnoticed until some player takes advantage of them, enabling some action with consequences the GM wasn't prepared for.

My instinct tend to be to just veto the action, declare a new houserule and continue on - but that is a terrible instinct. Instead, if this happens, allow the action, declare that it was a one-off and that a new houserule is in effect from now on, then handle the consequences. You, as the GM, is in deep homebrew territory, and it is your responsibility not to punish the players for things you hadn't thought about.

To avoid larger versions of this, it is therefore very important for players to be open with what they intend to accomplish when they are building their characters. If a player wants to build a character to take advantage of this mis-match between systems, then you need to announce the houserule and help them find some other idea to work with.

If they have already built for it once the GM discovers the problem, then communication has failed, but you as GM will still have to be forgiving. Let them rebuild the character as much as is needed not to get hurt by the sudden changes in how the world works.

An idea might even be to reward players with experience for their characters (or just a cookie for the player) when they discover potential exploits. They are basically playtesters, after all.

Player frustration

You, the group, seem to be heading from a simulationist paradigm towards a more narrativist one. This means players in the group may be, as the linked article suggests, "greatly concerned with the internal logic and experiential consistency". Compare this to what I wrote in the Unintended consequences section above, and you can see how the instincts of players may rebel, even if they have intellectually signed up for the experience.

This is not an easy problem to fix; maintaining in-group communication is really my best tip, here. Consider starting and/or ending each session with a short discussion of frustrations, problems and ideas, where players can vent and you can brainstorm for solutions.

No help online

Neither you nor your players will be able to find any real help on how to interpret and adjudicate what is very much your own custom system. For many systems, character ideas and build tips are available online, with fora devoted to discussing such. Your system is yours alone, unless you write up a more formal document to share with others.

Creating such a document and setting up a forum for discussions, as well as advertising both, might not necessarily be a bad idea, but will require a lot of work and you may still not get much engagement, if any.

Legalities

However, if you chose to make your ideas public and you're not careful in how you phrase yourself, you may be entering copyright territory. Mythic Europe in and of itself belongs to Atlas Games, but a "medieval Europe where many legends are real" does not. The Dreamlands are in the public domain, since H. P. Lovecraft passed more than 70 years ago.

Copying system concepts from another game is par for the course and generally covered under the "Fair Use" clause, but be sure to name your inspirations and don't actually steal - rewrite in your own words.

Have fun

If you and your group are not having fun, you're doing something wrong. Since you are already in deep homebrew territory, don't be afraid to change things. Use the pre- and/or postgame discussions to propose and revert changes - try to be consistent during sessions (see Unintended consequences) but if you want to try TBW spellcasting instead of the Ars Magica magic system for a session, do so.

Listen to your players, and talk to them so they know where you're at. The narrativistic paradigm puts much less emphasis on the GM always having to have all the answers. Work with each other, and make the game great.

Then do it again, and make it even better.