I've overhauled the OP again with updates, and I've done some mock-ups (edit: removed). Here are the changes explained:
Exhaustion - State
When you next have unused actions and it's your Action Phase, return this and -1 action.
Finalising what Exhaustion actually does. It only hits at the Action Phase.
Advancing Village doesn't have the option to discard on play, for simplicity and balance. It also can't be instantly played if it enters hand during your Action Phase, as making terminal draw non-terminal is crazy. It also calls for a little bit more play skill.
No changes to Blueprints, a neat enough trasher for the set. There's been a curious Actions and Treasures sub-theme developing, so it does fit.
No mechanical change to Canal, this hasn't been imbalanced yet though I've still to put it with Cornucopia.
Colliery needed to change when it took on Exhaustion. You can choose to carry Exhaustion over to your next turn to wait and see if you draw any Actions to play, and if you do you can spend an action token then to play them. If not, you keep your tokens. With the overpay it had, you could get too big a store of them, and that meant too many early Provinces.
Here's a
new idea, making Colliery the top of a split pile. I had the idea of this Treasure, since action tokens could make it work well. Tried it, but it was too much like a cheap early Platinum as a plain kingdom card. The fix I came to was this:
New Element - $5 cost.
When you play this, it's worth $5 -$1 per card in your hand, down to $0.
-
You may only buy this if you have a Colliery in play. When you buy this, return the Colliery to the Supply.
It seems to gel together with Colliery fine, I just wonder if the bottom part couldn't be better.
Cameo takes on the name Diary, it seemed better thematically. No change otherwise, it works well.
Entrepreneur is great, I see no need to change it.
Glassworks - Action, $5 cost.
Draw up to 8 cards in hand, then discard down to 5.
If you don't have Exhaustion, you may take it to reveal your hand and gain a card costing exactly $1 per type (Action, attack etc.) in your hand.
I did rename Steelworks to Glassworks, and with the Exhaustion change it needed a rebalance. You could do the draw and discard and make it non-terminal if you then revealed 2 Action cards, that as well as the possibility of +coins and buys. Too much power. Now you have to do the sift first, and the second part works with types in a different, hopefully interesting way.
Hawker makes the 0 or 2 cards buying work across the turn, because of Black Market and Innovator below.
Innovator - Action, $5 cost.
Choose one: + $2, play up to 3 Treasures from your hand, and you may buy a card, gaining it onto your deck; or +2 cards.
If you don't have Exhaustion, you may take it to do the other choice.
Dairy has gone for now, because I noticed how similar it was to Innovator (and hence I felt better about renaming Cameo to Diary, would be silly to have both names). This gets exactly the same vanilla with Exhaustion, though the buy is a little different. Perhaps now there's too much going on and it's too complex a card?
As Locusts are now a hex, I renamed the card Pigeon. No other change.
I renamed Refinery Potteries. It's prettier and feels a bit more Dominion-y. It's the same, complex like Innovator.
Revolters - Action Attack Duration, $4 cost.
Until your next turn, if each other player has 1 or fewer unused actions at the start of their Buy Phase, they gain a Curse; or if there are no Curses, a Copper.
At the start of your next turn, take an action token.
A wording change for Revolters, including giving out Coppers when the Curses run out. Diadem isn't attacked by this anymore.
Steelworks - Action Attack, $5 cost.
Gain a card costing up to $4; or if you have used 3 or more actions this turn it may cost $5.
Each other player reveals the top 3 cards of their deck; if one costs the same as the card you gained (they choose one if there are 2 or more), they may trash it or gain a Curse.
Steelworks's attack looks deeper into the other players' deck, 3 cards that are put back afterwards, and gives the option to gain a Curse instead of trash the card, because Knight attacks aren't popular.
No changes to Textile Mill. It gives a lot of control over your cards, but Exhaustion is a significant setback.
Tutor's discard and draw now applies just to cards neither Action nor Treasure, not 'Victory or none of these types'. It's shorter, simpler, and saves potential tracking issues like with played then discarded Nobles.
No change to Wastelands yet. In some games it's added a very nice rewarding challenge, trying to keep your deck small enough by the game end. But sometimes someone concentrating on them will 'seal themselves in' and make themselves unable to do any more until the game ends. The other players need only wait until they get more points before ending, a pretty boring wait.
As cards have left, I thought of
new ones and given them a little testing.
Night Shift - Night Duration, $5 cost.
Take Exhaustion; if you do, and the previous turn wasn't yours, take another turn after this one.
Thinking of Exhaustion has really helped me think of simpler cards that use them. How about a really good one that takes it for the start of your next turn? From there, this just followed on. It has such a natural feel to it, right down to its theme.
Parade - Victory, <8> cost.
Worth 8VP - VP equal to the difference in the number of Actions and Treasures in your deck.
-
You may only buy this if you have the same number of Actions and Treasures in play.
This one accentuates the Actions and Treasures thing in this set. There are Action-heavy engine strategies, and there's big money, but this encourages a balance of the two.
And finally, a big group that makes even more of Actions and Treasures, and tries out a bunch of different mechanics:
Components - Action Traveller, $3 cost
Return this and another Components from your hand to the Supply. If you do return 2 Components, gain a Prototype.
-
When you gain this, gain a Silver onto your deck.
A Traveller that upgrades Treasure Map style. Though you may choose to buy this just for a top-decked Silver at the same cost.
Prototype - Action Traveller, $5* cost.
Take two action tokens.
Trash a Treasure from your hand. Gain a Treasure costing up to $3 more to your hand.
You may discard this. If you don't, then at Clean-up exchange this for a Patent, Spinning Mule or Steam Engine.
(This is not in the Supply.)
A card that discards itself on play, so it can be played several times in the same turn. This mechanic can run into several issues, but Prototype should be safe from most of them. It has no issues with tracking, and it's impossible to make infinite turns with this as it's a non-Supply card.
It's only a 3 stage Traveller as Components are hard enough to upgrade. But the final step is a choice of three.
Patent - Action, $6* cost.
Choose one: +1 card, +1 action, +1 buy or + $1, then this becomes the card on your Patent mat.
-
When you first gain this, put an Action card from the Supply that isn't on another player's Patent mat onto your Patent mat.
(This is not in the Supply.)
Yes, Patent has moved. It created too much first-buyer advantage as a Kingdom card. Here, it can afford to go for any card cost as the timing and difficulty to get 1 of them balances it out, and the Patent mat banning can be fair as if there's a good target for it, probably one of the alternative upgrades will be good too, Steam Engine. So a Patent race won't leave the loser hopeless.
Spinning Mule - Action, $6* cost.
+1 card
+1 action
While this is in play, after you play a Treasure, +1 card.
(This is not in the Supply.)
The Treasures upgrade. It started as a permanent duration but you could get it so soon in some games that it dominated. You get the cards after resolving for no other reason than working better with New Element above.
Steam Engine - Action, $6* cost.
While this is in play, the next 3 times you gain a card take an action token, and when you spend an action token, instead of +1 action you may play an Action card from your hand twice.
(This is not in the Supply.)
And here's Magnate, moved, renamed and buffed a little. When it was a kingdom card, really you just wanted one of them. I already had Spinning Mule as an idea I was testing, and when I noticed how it upgraded Treasures similarly to this with Actions, this whole group happened.
And that's the lot. Wanderers I'll do later. (Is this still tl;dr?)