In City of Heroes, defeated Foes were the source of Drops ... that were either useful, could be traded or were vendor bait.
So what did defeated Foes drop that would go into your Inventory?
For the purposes of what we're talking about here, I'm going to "handwave" Experience and INF for the moment, although I am going to circle back around to them.
So ... Inspirations. Those are basically going to get subsumed into the Momentum/Reserves system. In City of Titans these will no longer Drop.
Enhancements. There actually does need to a "market" for these types of things in City of Titans, but using a random drop system like City of Heroes did is rarely all that useful in practice. Now, admittedly, City of Heroes had WAY TOO MANY FLAVORS of Enhancements to wade through, ensuring that MOST of what would Drop for you would be stuff you don't need, resulting in a glut of vendor bait (needed to buy the next round of SOs every 5 Levels until reaching the Level Cap).
Salvage and Recipes were only used for Crafting ... and Market PvP. But the way they "worked" in game was essentially as Permission Slips, granting characters "permission" to create Inventions.
Here's what I'm wondering ...
What If ... City of Titans doesn't have Enhancement Shops covering specific Level ranges ... because Enhancements (or Boosts, or whatever City of Titans is going to call them) are ALL crafted by Players ... rather than being "bought" from an NPC who has an infinite supply of the buy, and Dropped by Foes that are always respawning and getting Defeated.
So instead of going and "buying" your Enhancements, you go to a Crafting Station and MAKE your Enhancements.
Alright, so instead of having TO/DO/SO/HO ... instead you've just got IO. Inventions only.
The major effect of going to an Inventions Only system means that Enhancements would only be MADE ON DEMAND rather than Dropping whether you wanted them or not. It would also mean that there could be a Market(!) for crafted Enhancements in which people who don't want to go to the trouble of making them can just "pay someone else" to do it for them.
Okay ... but how would these Inventions get made?
Well ... if you completely dispense with Salvage and Recipes, what are you left with for crafting materials? Reserves, Experience and Currency (ie. INF).
So imagine if making any of the Enhancements you needed simply cost you Reserves, XP and INF.
The Reserves cost would substitute for the Salvage and Recipes system and would represent "banking" a portion of your combat actions for future use.
The XP cost would be one of those voluntary things where you expend a fraction of the Total XP to your NEXT Level Up (say, 5-10%) per Enhancement you Invent. If this cost would put you below the threshold of having enough XP to be your current Level then you can't Invent another Enhancement until you've got enough surplus in your current Level to clear this requirement. NOTE: this would mean that the Level Cap wouldn't be Level 29 completed +1XP more like City of Heroes did, but instead the Level Cap would be a "Full Level" of XP that could be drawn down to "spend" to make Inventions with.
The INF cost is self explanatory. We know what "currency" is used for.
With such a "Invent Rather Than Vendor" system you'd have something where PCs at the Level Cap have a "sink" allowing them to burn off their excess resources in a way that can benefit the entire community of the game through the medium of a Market.
Set up the Inventions to be "Level Agnostic" such that they don't suffer Level Decay (like TO/DO/SO did) and you'll be able to get both a Supply and a Demand for these Inventions going ... AND have it be one where the NPCs can participate in that Market in such a way as to be a moderating influence and overall "sink" for excesses of resources that the game generates so you don't wind up with flooded markets and hyper-inflation.
The virtue of such a system is that rather than dumping Inventory upon the PCs and then making it the Player's responsibility to "dispose" of all those Drops ... instead the Players have to be able to Plan Ahead and anticipate what they're going to need (or what the Market "needs" right now) and jump through the hoops accordingly when it is convenient for them to do so. Also, without an Enhancement Decay system in place, Inventions are "eternal" ... barring some kind of Death Penalty system or other means of "destroying" Enhancements once they've been slotted (note: not required, but an option). This means that Inventions slotted at Level 1 could still be in use at Level Cap, because the Inventions themselves are Level "agnostic" in the larger scheme of things, leveling the playing field and consolidating the market.
An additional side effect of such a system would be that Inventory space could be kept relatively small (ie. 10 slots should suffice) since there wouldn't be all that much pressure to store massive quantities of "stuff" on your PC (except for really major Market PvP actions).
Verbogeny is one of many pleasurettes afforded a creatific thinkerizer.