Best toolbox RPG to start with?

[rhythmsoundmotion]

I do have an idea for a steampunk game. But the idea has so many uncertain, undefined aspects that it would benefit from the restrictions of a game system. And seeing how different systems restrict the idea could spark some good ideas (I hope anyway.)

In the end I suspect the idea is not feasible. But, it will probably teach me a lot trying.

 

[dbm]

The dream toolbox RPG would support all the play styles But a more realistically possible one would probably have modularity that allows changing different play elements to fit a specific campaign idea. It would probably have a default play style, but changing the default would require assembly and fine tuning.
But, I don’t know that I have ever read a thorough description of toolbox RPG

All the toolbox and genre-flexible systems will do that, with more or less work required. The trick IMO is to know what your default style is and mostly work from that one.

For me personally I like action adventure which makes Savage Worlds my start position. You can tune up or down from there. There are optional rules for gritty damage and skills specialisation if you want to tune down the feel and make the characters more grounded. And there are optional rules for damage caps and a super powers system if you want to dial it up (there is also the Rifts implementation which, of course, dials things to 11).

The well established systems all have good guidance for how to implement a type of game:

In terms of play styles, again they will give you more or less tools for different things. And over time when you internalise the tools you will see how to implement other things with them. I’ve spent the last 5-6 years focussed on Savage Worlds and now I really understand how the mechanics work and I find it super-easy to customise to my specific game.

The others are pretty much the same, just from different baselines. I was primarily a GURPS player and GM for about 15 years before that and, again, I really got to know that system. I switched because the default position of GURPS (‘real world verisimilitude’) wasn’t what I was playing very often anymore and that meant I was doing customisation every game to move it to action-adventure which is Savage Worlds baseline.

Systems with worked examples are the easiest to get for me, it depends on your own learning preferences though. Reading Deadlands, Pathfinder for Savage Worlds and Savage RIFTS really helped me see how the game’s designers saw customisation working.

The fully toolbox systems (Fudge and Cortex Prime) will require more work which is a double-edged sword. More effort but more customisation because your system will be somewhat hand-crafted.

 

[aramis erak]

The PDF prices of D6 Space, D6 Adventure, and D6 Fantasy are great! Is there any advantage to one of the versus the others?

Yes, but it's pretty subtle... D6 Space was originally slated to be Star Wars 3rd edition... but LFL pulled their license. It retains the WEG Star Wars force powers, relabeled as psionics. Adventure is the same core, but with different attribute and skill names and a few different options as standard; it has a build your spell magic system and a second (different from Space) Psionics system.
Fantasy has a similar (If not the same) magic system as Adventure, but has a religion/miracle system, and some more attribute and skill name changes and differences.
All have a wound level option and a hit points option.
all three have the same base vehicle rules, but different vehicles in the lists...
Space is a star wars derived list of equipment.
Adventure is a modern list.
Fantasy is, of course, faux medieval.

There are just enough options to be customizable in the rulebooks, and by mix-n-match of the paranormal abilities across the three, and attribute mix-n-match, you can tweak the feel of the attributes while making no substantial mechanical changes.

Space feels a touch more complete, but it's more about tech and tone. And they are fully interchangeable mechanically; the names were changed for feel, not substance. Pick for desired feel - Space is great for SW, doable for Trek or Orville (with some new template creation). Adventure is for moderns and Indiana Jones, and can do horror as well. Fantasy is... not Herc and Xena.
(H&Z was a variant using only whole dice... )

 

[Thondor]

I recently released an Alpha playkit of Fabrication: A game that makes games

It's maybe a little past a toolkit game. It is a game design game, that can help you pick all sorts of base assumptions (like number of players and how you divide authority) as well as construct and play-test wildly different mechanics.
You can read more here Fabrication: A Game that makes Games