A discussion for an Offline engine + potential Singleplayer Content

This thread is about the suggestion for making an offline engine for the Spiral Knights franchise.
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This suggestion is half one of it's own and half one in relation to the Workshop suggestion I posted earlier:
http://forums.spiralknights.com/en/node/114478
The argument:
1) Map maker
An offline engine would allow users to make map submissions, as well as playtest them locally. This would work best with the Workshop Suggestion and could easily be included with the MMO in Steam (Much like many other steam gaming including SDK tools)
2) Singleplayer Content
The engine for the game exists and is pretty robust. While it wouldn't be a lot of content, an offline singleplayer engine for new content or even single-player only missions would be fun no matter official or not.
For official content it could evolve into it's own sort of game, but if used with the workshop it would make it so people are playing your game/engine without needing to rely on your servers. Saving money while also increasing player involvement.
The basic tools could be included in SK while if you do make an offline game with content, it could be a separate program on Steam. (which you could probably charge a small amount for). You may think it could potentially drive people away from the MMO, but if it's just an accessory the MMO people will still play the MMO and get the tools with the MMO anyway.
Those who don't probably would not have anyway if the limited SP content satisfied them.
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This suggestion is probably the most involved, but if combined with Optimization and Workshop I believe it would be a great boon for both the players and Grey Havens. Not only in terms of making the game better, but also providing a more robust engine and tools for allowing future content and even games.
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If you have any opinions on this please comment as well.

The offline content would be separate from the MMO, as it should be. Either via a SDK tool to test the level or via a separate download/"game"
Tools to create levels for submissions (anywhere Grey Havens would accept them, Steam Workshop would the easiest to curate and fine submissions, but it's not limited to that)
Tools to test levels (which means you can test other players levels, usually integrated in the level creation tool)
If these tools were created (either for or not for player consumption), Grey Havens would be a few short steps from making a small offline game where players can make fun little scenerios and such using the tools, in a more polished play environment than the tools potential test-run feature. This would not be an end-goal as this suggestion itself is to provide the ability for level creation, which also would need an avenue of submission and anything else beyond that is just bonus.
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If you wish to see another successful game that used both Steam Workshop as well as player-ran mod websites and also a modding sub-forum, check out Torchlight 2. That game had allowed both downloaded and workshop mods. While my suggestion does ask for Workshop, the only thing that would most likely be usable without the game updating to include them would be testing level segments, via the offline tools provided.
All submissions that would be included in the game (where everyone can play the content, steam or not) would have to be curated and included by Grey Havens staff, so there would be no threat to exploits there as well.(Due to it being an MMO, active modding would be exploitable, so content people can use would have to be approved.)
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Please keep the discussion on point. I understand everyone doesn't like Steam, but just because a suggestion includes Steam as a point doesn't mean the entire suggestion is only for Steam and against everything not-Steam.
Steam is a tool, one that already has a lot of integration with Spiral Knights. To not use it would be throwing money out the window.
Steam's submission and content creation part of Workshop would not need a Spiral Knights account to be linked to your steam account, so there would be zero detriments in using it as an already established avenue other than the fact it's Steam. (Which is not a good enough reason if it doesn't restrict other avenues)

I don't think it's bad to see old suggestions again if they are vigorous and ambitious in nature (and not carbon copies or lazily done). Now if he suggested this stuff with no context or substance, and just said "pls OOO's, gimme dis", then there would be a problem here.
I specifically remember in the latest 20 threads people have posted on this
the game is an mmo, by adding offline modes you ruin the intent of community
this has security risks (I dont remember the details someone gave)
Single player content: just click the solo button
The steam superiority complex is strong with this one