MTG Salvation

But what about the cards that assemble contraptions?

Those weren't intended as actual designs. I was just proposing the idea of that sort of cycle.

And yeah, a few more mechanical ideas are needed. Possible space to explore:

-Utilizing equipment as necessary enhancements (bonuses when equipped?)
-Metalcraft? I don't think that mechanic was received too well, though.
-I had an old keyword called 'Tinker'. You sac an artifact and tutor for one that costs less, putting it onto the battlefield from your library. Perhaps, if paired with "artifact ETB / LTB" effects on cards, this could make for interesting situations? It did seem a little narrow, though - I only did it as a one-off for a challenge.
-We discussed Contraptions / assemble earlier. Those are possible design space.

I think a cycle of those colorless lands that have activated abilities at common would also greatly help - perhaps they could represent lands that have been ravaged for all their mana, and have installations planted in them? For instance, uhh...

Observatory Spire
(Artifact?) Land
:symtap:: Add to your mana pool.
:symu:, :symtap:: Look at target player's hand.

Furnace Core
(Artifact?) Land
:symtap:: Add to your mana pool.
:symr:, :symtap:: Target creature has haste until end of turn.

...and so on, and so forth.

I like this suggestion as well! Much better than my original idea. Colorless mana represents the barren deserts, technological cities, and the 'neutral' manifestation of progress, steam. I like it as a whole!

Perhaps some cards get a bonus for each colorless mana to cast them (inverse Sunburst, even)?

Marsh Gas
Creature - Spirit
Deathtouch, haste
At the beginning of the end step, sacrifice Marsh Gas.
1/1

Next : Pyre Charger

Youthful Recruit
Creature - Human Soldier
This creature untaps during every player's untap step.
1/1

Perhaps it could depend on color? Some colors prefer colorless, others prefer using their own color?

Maybe even depend on faction.

Those look familiar. I think I saw them in another thread?

Well, I probably should have mentioned... I was only imagining artifact-mana on colored cards! It'd represent the inventions and tools of the society being harnessed for power and energy. (If you can't tell, flavor is a big thing for me)

Here are some examples:

Steam Blast
Instant
Steam Blast deals 2 damage to up to two target creatures.

Something along those lines.

On instants / sorceries, it represents magic and technology mixing and mingling.

On creatures, it'd just represent a tool being used, or technological-influence making artifacts necessary for existence. For instance:

Security Guard
Creature - Human Soldier
, :symtap:: Tap target creature.
1/1

(Sorry the alignment is a little messed up with the icon. I just quickly grabbed it for example purposes.)

Shield of Purity :1mana::symw:
Enchantment - Aura
Enchant creature
Enchanted creature gets +0/+2 and has protection from creatures.
"May you never touch the sin of flesh. May you never behold the sin of existence."

Raging Behemoth :1mana::symrg::symr:
Creature - Beast (C)
Trample, haste
4/2

I imagined the symbol as a grey-circle with a gear in it, to help save text-space and such on the higher rarities. And remember, it could be used for activated-abilities in higher-rarities as well!

And thanks for the compliment, BlackVise!

Why is Arcane Denial an artifact? I don't really see the name befitting one.

Psychatog :1mana::symu::symu:
Creature - Atog (R)
Exile a card from your hand: Psychatog gets +1/+1 until end of turn.
1/2

Next: Cloud Crusader

The Lure problem is probably a reason to make Starfall Shaman have a coin-flip, as Oculus suggested. Or maybe it could have a mana cost?

Quote from The Most Curious Thing

"Assemble" is the obvious keyword -- should it be an alternate casting cost? Provide alternate effects? Make token copies?

I'm also thinking we should consider "disassemble" as the flipside of assemble -- sacrificing the Contraption for a one-off effect? We can also make liberal use of "whenever you (dis)assemble CARDNAME" and, for Riggers, "whenever CARDNAME (dis)assembles a Contraption."

Perhaps Contraptions could be simple: "assemble a contraption" = "put a 0/1 colorless Contraption artifact creature into play."

For an innovation for the set, I was thinking of using "artifact mana" - a cost that basically means "pay or tap an untapped artifact you control"? That feels like it'd require balancing.

Having lots of Contraptions, Assembly-Workers, "passive" Artifacts, and Equipment works well for this - instead of Mirrodin, which emphasized artifact-creatures and metallic-lifeforms, this is a world where people just use artifacts as tools of progress. The people here aren't metallic in nature, nor is there a thriving artifact-creature ecosystem.

The flavor there is pretty good, I feel. Equipment requires a creature to attach to -- Assembly-Workers (which is a FANTASTIC suggestion) are servants and worthless on their own, generally -- and Contraptions have to be built by something else, and their main purpose is to act as fodder for their masters.

The more 'constructive' artifact types (:symu: and :symw:) would probably enjoy making Contraptions, and using them for passive effects, like "artifact-mana" or blockers.

The more 'destructive' artifact type (:symr:) would use them as fuel, by disassembling them for fodder or for scrounging out their parts (to make better things).

and are the outliers, there -- I personally feel enjoys Equipment (which synergize with creatures well).

being based around artificial enhancement and horribly-mutilating the boundary between life and death also fits well with Equipment. Think Nim Deathmantle, or Demonmail Hauberk.

Hopefully this is a helpful suggestion! I really do like the idea of a Steampunk set, and you guys are going places, I can tell. I'd be glad to hop in and assist with this.