Introduction
If it is the case that the Radiant Crystals ARE for making money, then a way around selling them as a main source of profit would be needed. The old energy system was quite ingenious, but gave a bad vibe to newer players, and arguably (but only arguably in a different thread, safe from derailment :P) had to be replaced for the game to improve. The current system minus the radiant drought is equally appealing, but seems to have mis-fired in the slightest.. if the radiants ARE for making money then the newer system wasn't performing well.
We would need a way to do this that would be both equitable to players, and profitable for the developers more profit equals more development, which in turn equals "add weapon at Spiral Knights", but faster. If we get this, then the game will have much better odds at being a "great game" someday, which is what I would hope we're all aiming towards. If Spiral Knights does work out this way, it would grant it more development time from OOO and Sega, allowing for bug fixes and optimization at a faster rate... eventually becoming smoother running, more polished, and better played in terms of artistic development (i.e. No more light blue devilites on light blue snow with light blue grievers dropping light blue mist).
The other side of this issue, which I think deserves another thread would be how to sell Spiral Knights to newer players. But I'll save that for another day <3.
Plausible Options Suggested by Myself and Others Below
These are the ways that I myself have observed and thought of. Feel free to share other ideas- thats the point of having this! Also consider that this isn't set in stone, a melding of these and other ideas might just likely outperform any specifics. I'll update this and other sections later.
===Costume Store: Selling Fashion in Any Fashion===
I think that the costume items being sold in the supply depot requires a larger player base to work. More players = more buyers and it all snowballs. Thats how Team Fortress did it- they built a strong community, and then monetized it. The other part to this is that it requires a steady flow of items with interesting models to work, taking up resources. Other games being Team Fortress 2 have utilized the community for this, giving them some of the profit on the items they make as if they are employees- furthering positive vibes about the game.
This would take a lot of time to set up, though further partnership with Valve could speed up the process, but exclude players coming from other community. An in game editor would take a huge amount of time to develop.
(Sweet-Hope) A redux of the prize box system could help sales of in game items quite a bit- where prize boxes have unique items that will never be sold in the supply depot, and the supply depot has interesting items of its own. Stratifying boxes (e.g. "onyx prize box: Heavy maid headband, volcanic dragon wings, super-prismatic halo...") See: http://forums.spiralknights.com/en/node/95492#comment-854900
(Sereos) And some random ideas for the "special rare item" could be some otherwise unobtainable things like a black/white personal color, Extra Short/ Extra Tall Height Modifier, shiny re-skins of 5* weapons/armor, special character badges or how about a "kill counter" that you can add to weapons.
I myself do like the idea of a shiny re-skin of 5* weapons... but what if it was an item called "weapon sheen", and it was applied to weapons to give them a particle effect and make them sparkle? Auras for weapons would be nice, in fact, quite a few people in quite a few threads have asked for weapon and shield customization to go with the costumes. This alone could easily be the greatest new thing for a while.
(Sereos) Moving certain items that Vatel sells to the supply depot would be necessary- things like eyes, colour mods, and height mods are out of place bend sold for crowns and would better be sold for energy. See: http://forums.spiralknights.com/en/node/95492#comment-855281
===Selling Gear/Progress Fairly in Some Way===
The original intention of the energy system was to limit the ratio of paying and non-paying members to a ratio. It relied off of players that cared for the game deeply enough to have faith in the energy system and pull through, buying and selling energy on a regular basis.
Something like this *could* be attained, but would have to be done in a way that made it seem fair to the players. In my eyes it would need to avoid giving a massive edge to a minority of players to work.. things like unique variants allow for this to work well for to this end (with the exception of lockdown, UVs are relatively unnecessary). Things like buying and heating weapons do not, though the upgraded system of buying weapons was far more fair and lenient, while still holding true to the model of selling players content. I think this model is vaguely acceptable, as long as it isn't entirely needed to progress- which raises the issue of players not buying into it at all and the game not profiting from it.
(Sir-Didymus) "Introduce more expansion missions, but make them available to all players for a small fee. An example which should not take much work would be an adapted Royal Jelly Palace with a shock theme. Adjust the difficulty to be between T3 and shadow lair. Create a new type of box which drops an orbs of alchemy or 3 radiants to place at the core room post mission, and make the mission playable only once per day. It would provide a way for players who pay to receive a few radiant per day, but not be able to be farmed."
This idea could be utilized, though it'd be nice if they just you know... made the shadow lairs into expansion missions? This would also make them seem far more just, and would likely get a lot more energy per player, if they cost the same as OCH.
(Katherine-Dragon) Hey, you forgot DLC!- http://forums.spiralknights.com/en/node/95492#comment-856142
Additional DLC would be another good way to go, though there is always the concern (or at least there was last time) that the game needs more free content for the veterans, whom have already paid to just join the community of veterans and are continuing to pay. If additional DLC IS added, I think the shadow lairs would be the best candidates. Another OCH type thing- that is, actual new content- would be plausible though I believe a new model is needed for this.
===Premium Accounts and Various Passes===
The idea with these is that you buy some sort of pass that would grant you a number of things. I would suggest offering this pass, or these passes separately, for energy or even crowns as well as actual currency- this would allow an easy avenue for F2P players to get the items, and would make the game seem more justified in having them there. This pass could:
(Kathrine-Dragon) Allow players more control over the levels. See http://forums.spiralknights.com/en/node/95492#comment-854901
Another idea for implementation of this can be found here: http://forums.spiralknights.com/en/node/95492#comment-854954
(Hyper-Galactic) Shadow lair pass (would be hard to do justly, as Hollows points out), monthly coin doubler, and best of all- access to sent mail. See http://forums.spiralknights.com/en/node/95492#comment-854925
The idea of selling extra friend slots or access to sent mail for some CE price does seem promising... just like trinket slots. You could do any number of these kinds of "passes" or abilities, and then charge a small amount for them. Improved auction house? The only draw to these kinds of things would be that it'd make the game come across as being incredibly greedy if every single feature was locked behind some wall that could be paid for in one month, and that I really can't see many people paying a monthly fee to unlock their mail sent folder.
My suggestion? Give the features to all accounts that buy any energy. The reasoning being that its a foot in the door- once people buy something once they're far far more likely to do it again- something far more valuable than a simple CE sink that would turn just as many players away.
But like Ardent-Light said, we don't want to make the game seem too much in the way of favoring the P2Pers. Allow F2P players to buy these features and make their account "paid" for a sum of energy- like 2,000 or so.
(Ardent-Light) A way to skip levels for energy would be another idea- here detailed to cost more per stratum, though I'm not certain if that or a set price of 50 CE would be better. See- http://forums.spiralknights.com/en/node/95492#comment-854954
===The Kickstarter Method - Charging for Future Content and Rewarding Direction. (my vote, if any)===
Kickstarter often has certain prizes for high paying individuals. OOO could also do this- with each energy purchase players make, they'd get a vote towards what new content, costumes, and confetti would come out. OOO would give us their agenda, and would work towards whatever goals were reached. The goal would be set according to the forecasted profits, and would explain that OOO is a small subsidiary of Sega with a relatively small dev team. The goal would be to help them expand their arsenal of programmers, developers and artists, as well as to create content that the players want.
Things that are vital to the game or supported largely by F2P players but might not garner support would still be created alongside the P2P chosen content, but would offer less direction on the part of the players. F2P players could also use their minerals (or a new pure mineral of some sort) to vote on new content, and P2P players could be given minerals to use as votes.
If I'm a P2P player and I don't like any of the options, I'd likely choose to vote for confetti or costumes instead. If everyone votes for "more swords!" then the game will get more swords, and it will be taken off the menu for a while, until the game is made to be more balanced towards the other weapon classes.
OOO could also have players pay for earlier releases- say they had put off the gunner update till February. It'd still be done around January, but they wouldn't release it immediately and would develop other content... so that the game wouldn't be slowed. No, they wouldn't say "HOSTAGE SITUATION! NO GUNNER UPDATE! PAY UP!", just "We'll work faster if money is gathered faster = better development." This would further incentivize players to work wight he developers rather than against them.
U-77654 brings up a good point at the end of his post, that steam users who buy keys would be disinclined to do so if there were a voting system.
Rating offers exactly why I wrote this section in another thread, and I think its important to keep this sort of logic in mind... we aren't just buying into some system, we're supporting OOO- http://forums.spiralknights.com/en/node/95577#comment-855751
===(Sir-Didymus) Expand into Other Markets===
"Enable unbound items to be sold on the steam community market as an additional revenue stream."
The players- at least the steam players- want this. If your product is good enough, that is, comes across as being just to players, this alone will draw in a larger community. Like with the iron costumes, steam users forced to make an account and merchant their items in Spiral Knights might just get stuck playing Spiral Knights.
But lets say that Kongregate has a system similar to the steam-market-- this should be used too. All systems that Spiral Knights can be expanded into should be utilized.
tl;dr
dude! 500 words or less...just sayin....